Circular No. 27/2010/TT-BGTVT Issuing National Technical Regulations on hydraulic steering gear on watercraft - technical requirements and testing methods

CIRCULAR

Issuing national technical regulations on hydraulic steering gears for watercraft - technical requirements and testing methods

Pursuant to the Law on Standards and Technical Regulations dated June 29, 2006;

Pursuant to Decree No. 127/2007/NĐ-CP dated August 1, 2007 of the Government detailing implementation of certain provisions of the Law on Standards and Technical Regulations;

Pursuant to Decree No. 51/2008/NĐ-CP dated April 22, 2008 of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Transport;

The Minister of Transport hereby promulgates:

Article 1. Issued along with this Circular are the National Technical Regulations on Hydraulic Steering Gears for Watercraft - Technical Requirements and Testing Methods;

Registration code: QCVN 24:2010/BGTVT.

Article 2. This Circular takes effect six months from the date of issuance; Repealing Decision No. 07/2006/QĐ-BGTVT dated January 18, 2006 promulgating Industry Standard 22 TCN 343-06 "Hydraulic Steering Gear for Ships - Technical Requirements" and Decision No. 08/2006/QĐ-BGTVT dated January 18, 2006 promulgating Industry Standard 22TCN 344-06 "Hydraulic Steering Gear for Ships - Testing Method at Workshop".

Article 3. The Heads of the Ministry's Office, the Inspectorate, the Departments, the Director of the Vietnam Register, the Heads of units under the Ministry of Transport, relevant organizations and individuals are responsible for implementing this Circular./.

AMENDMENT 1:2025 QCVN 07:2023/BXD

QCVN 24: 2010/BGTVT

Technical standards national technical regulation on hydraulic steering gears for ships technical equipment and test method

National Technical Regulation on Hydraulic Steering Gears for Ships Technical Equipment and Test Method

 

Foreword

QCVN 24: 2010/BGTVT replaces 22 TCN 239 - 97.

QCVN 24: 2010/BGTVT was compiled by the Vietnam Register, reviewed by the Ministry of Science and Technology, and issued by the Minister of Transport pursuant to Circular No. 27/2010/TT-BGTVT dated September 9, 2010.

 

TABLE OF CONTENTS

Chapter 1. GENERAL PROVISIONS

1.1. Scope of Application

1.2. Applicability

1.3. Definitions

1.4. Referenced Documents

1.5. Drawings and documents

1.6. Operation guidance display

1.7. Operation and maintenance guidance for steering equipment

Chapter 2. TECHNICAL PROVISIONS

2.1. General requirements for characteristics and layout of hydraulic steering gear

2.2. Characteristics of main steering gear

2.3. Characteristics of auxiliary steering gear

2.4. Piping

2.5. Restarting and loss of power alarm for steering gear

2.6. Standby power source

2.7. Electrical installation for hydraulic steering gear

2.8. Position of steering gear

2.9. Communication means

2.10. Rudder angle indicator device

2.11. Control system

2.12. Materials, construction, and durability of hydraulic steering gear

2.13. Additional requirements for tankers carrying liquid cargo, liquefied gas carriers, and chemical tankers with gross tonnage of 10,000 tons and above, and other vessels with gross tonnage of 70,000 tons and above

2.14. Special requirements for hydraulic steering gear used on ocean-going vessels

2.15. Special requirements for hydraulic steering gear used on ocean-going vessels operating in restricted waters

3. MANAGEMENT PROVISIONS

4. RESPONSIBILITIES OF ORGANIZATIONS AND INDIVIDUALS

Chapter 5. ORGANIZATION OF IMPLEMENTATION

 

AMENDMENT 1:2025 QCVN 07:2023/BXD

On hydraulic steering gears for watercraft technical requirements and testing methods

National Technical Regulation on Hydraulic Steering Gears for Ships Technical Equipment and Test Method

Chapter 1. GENERAL PROVISIONS

1.1. Scope of Application

1.1.1. This standard specifies technical requirements related to design, manufacture, installation, import, use, inspection, testing, and certification of various types of hydraulic steering gears for watercraft.

1.1.2. In addition to complying with the provisions of this standard, hydraulic steering gears must also comply with the provisions of relevant laws, standards, technical regulations, and guidelines applicable to each type.

1.2. Applicability

This standard applies to organizations and individuals involved in the design, manufacture, installation, import, use, inspection, and certification of hydraulic steering gears for watercraft throughout the country.

1.3. Definitions

1.3.1. Main steering gear (Main steering gear)

A system of equipment including the main power unit (Main power unit) and its drive system. The main steering gear has the ability to provide the largest steering torque to the rudder shaft to meet all operational conditions of the vessel.

1.3.2. Auxiliary steering gear (Auxiliary steering gear)

Another system of equipment necessary for steering the vessel in case the main steering gear fails.

1.3.3. BoManual emergency pump (Emergency hand pump)

A manually operated hydraulic pump that generates energy to drive the steering mechanism when the ship's electrical supply to the main and auxiliary electrically driven steering gears fails.

1.3.4. Power unit (Power unit)

A group of devices consisting of an electric motor with accompanying electrical equipment and a hydraulic pump with functional valves.

1.3.5. Drive system (Power actuating systems)

A hydraulic and mechanical assembly to create force to turn the rudder shaft, including the rudder actuator, tiller, cylinder mounting, safety valves, stop valves, pipes, and accessories. The drive system of the hydraulic steering gear must be designed to ensure that the rudder turns equally from right to left and from left to right.

1.3.6. Rudder actuator (Rudder actuator)

A device directly converting hydraulic pressure into mechanical action to move the rudder. It can be a rotary cylinder, single-acting cylinder, double-acting cylinder, hydraulic motor, etc.

1.3.7. Control system (Steering gear control)

An assembly of electrical equipment and wiring used to transmit control signals from the control position to the actuating mechanisms.

1.3.8. Tiller (Tiller)

A mechanical structure part transmitting torque to the rudder shaft.

1.3.9. Cylinder mounting (Fitting)

A mechanical structure part transmitting external force torque from the rudder to the base plate attached to the hull.

1.3.10. Safety valve (Safety valve)

A hydraulic valve protecting the equipment and piping of the drive system when hydraulic pressure exceeds the design pressure due to external force acting on the rudder.

1.3.11. Stop valve (Stop valve)

A hydraulic valve isolating the damaged section of the pipe to maintain steering capability in the remaining sections.

1.3.12. Check valve (Pilot check valve)

A hydraulic valve ensuring the rudder remains in any position by automatically separating the hydraulic circuit of the steering drive system from the hydraulic circuit of the hydraulic steering gear when control is terminated.

1.3.13. Relief valve (Relief valve)

A hydraulic valve automatically discharging oil from the pump when pressure in the system exceeds the maximum working pressure.

1.3.14. Maximum working pressure (Maximum working pressure)

Hydraulic fluid pressure in the system when the hydraulic steering gear produces the rated torque.

1.3.15. Design pressure (Design pressure)

Pressure used to calculate and determine the specifications of pipes and other components of the hydraulic steering gear. The design pressure is selected as 1.25 times the maximum working pressure.

1.3.16. for Vehicle Inspection

Vietnam Register - Vietnam Register (VR).

1.3.17. GT

Total displacement of the vessel.

1.3.18. Manufacturing facility

Organizations and individuals producing, manufacturing, repairing, converting, and assembling hydraulic steering gear and parts used for manufacturing hydraulic steering gear.

1.3.19. Design facility

Organizations and individuals engaged in providing design services for hydraulic steering gear.

1.3.20. Testing facility (test station, laboratory)

Testing facilities, test stations, laboratories (hereinafter referred to as Testing Laboratory) of domestic and foreign organizations operating in the field of material testing, hydraulic steering gear, and parts used for manufacturing hydraulic steering gear, which have been evaluated, certified, or recognized by the Vietnam Maritime Administration Inspection Bureau.

1.3.21. Equipment owner

Organizations and individuals managing and operating hydraulic steering gear.

1.4. Referenced Documents

1.4.1. International Convention for the Safety of Life at Sea 1974 (SOLAS 1974, Consolidated Document 2004) and its amendments and modifications.

1.4.2. Rules of the International Association of Marine Registrars (IACS) on hydraulic steering gear and its amendments and modifications.

1.4.3. National Technical Regulation - QCVN 21: 2010/BGTVT - Classification and Construction Regulations for Steel Hull Seagoing Vessels and its amendments and modifications.

1.4.4. Vietnamese Standard - Classification and Construction Regulations for Inland Waterway Vessels TCVN 5801: 2005 and its amendments and modifications.

1.5. Drawings and documents

The construction drawings and technical documents of hydraulic steering gear must be reviewed by the Inspection Bureau. Specifically:

1.5.1. Drawings

(a) General layout drawing of the steering equipment;

(b) Details of the rudder stock;

(c) Assembly drawing and details of the hydraulic steering gear;

(d) Assembly drawing and details of the rudder drive mechanism;

(e) Hydraulic system schematic and hydraulic piping diagram;

(f) Control and electrical system schematic (including alarm devices and automatic steering);

(g) Layout and schematic of the standby power source;

(h) Rudder angle indicator schematic;

(i) Other drawings deemed necessary by the Inspection Bureau.

1.5.2. Documentation

(a) Technical characteristics;

(b) Operating instructions (including drawings showing the switching procedures between different hydraulic steering gears and control systems. Drawings illustrating the automatic power supply sequence from a standby power source, data on type, technical characteristics, and assembly of the power source when it is independent, and the characteristics of the hydraulic fluid);

(c) Documentation on measures to take in case of individual failures in the transmission system;

(d) Strength calculation of important components;

(e) Other documentation deemed necessary by the Inspection Bureau.

1.6. Operation guidance display

1.6.1. Simple operating instructions accompanied by block diagrams showing the switching procedures for hydraulic steering gears and control systems must be permanently displayed in the bridge and steering gear room for vessels equipped with mechanical steering gear.

1.6.2. If there is an alarm device when the system fails as required by 2.11.1.4, appropriate instructions on handling procedures during alarms must be provided in the bridge.

1.7. Operation and maintenance guidance for steering equipment

Operating and maintenance instructions for steering gear and mechanical drawings of the steering gear must be provided. These instructions and drawings must be in both Vietnamese and English so that officers and crew members can understand the information when performing their duties.

Chapter 2. TECHNICAL PROVISIONS

2.1. General requirements for characteristics and layout of hydraulic steering gear

2.1.1. Mechanically driven hydraulic steering gear must have technical characteristics and structure of manual hydraulic steering gear checked by the Inspection Bureau in each specific case.

2.1.2. Each ship must be equipped with at least:

- One main steering gear;

- One auxiliary steering gear.

The main steering gear and auxiliary steering gear must be arranged such that the failure of one does not disable the other.

The auxiliary steering gear may share the drive system of the main steering gear.

2.1.3. If the main steering gear consists of two or more identical power units, then an auxiliary steering gear is not required, provided that:

(1) On passenger ships, the main steering gear has the ability to control the rudder operation as required by Section 2.2 when one of the power units fails.

(2) On cargo ships, the main steering gear has the ability to control the rudder operation as required by Section 2.2 when operating with all power units.

(3) The main steering gear must be designed so that after a single fault occurs in its piping system or in one of the power units, the faulty part can be isolated from the system to maintain or quickly restore the ability to control the ship.

2.2. Characteristics of main steering gear

The main steering gear must:

(1) Be able to turn the rudder from 35° on one side to 35° on the other side when the ship is at its deepest loading draft and moving forward at maximum operational speed, and under those conditions, the time to turn the rudder from 35° on one side to 30° on the other side must not exceed 28 seconds.

(2) Be operable mechanically if necessary to meet the requirements of (1) or in cases where the diameter of the upper part of the rudder shaft exceeds 120 mm according to the requirement (calculated with a factor dependent on the material K = 1, when K < 1), and excluding the reinforced portion (subsequently considered similarly) and_{"7. A flexible power plant is a thermal power plant using reciprocating internal combustion engines (RICE) or aeroderivative gas turbines (Aero-GT) with fast start-up capabilities, designed in modular form to generate electricity for balancing capacity and maintaining power system stability."} (3) Be designed so as not to fail when reversing at maximum speed. However, this design requirement does not need to be proven through testing at maximum reverse speed and at the largest rudder angle._{"7. A flexible power plant is a thermal power plant using reciprocating internal combustion engines (RICE) or aeroderivative gas turbines (Aero-GT) with fast start-up capabilities, designed in modular form to generate electricity for balancing capacity and maintaining power system stability."} Auxiliary steering gear must:

(1) Be capable of turning the rudder from 15° on one side to 15° on the other side within 60 seconds when the ship is at its deepest loading draft and moving forward at a speed equal to the larger value between half of the maximum operational speed and 7 knots; and be capable of being brought into operation quickly in case of an emergency; and

2.3. Characteristics of auxiliary steering gear

(2) Be operable mechanically if necessary to meet the requirements of (1) and in all cases where the diameter of the upper part of the rudder shaft exceeds 230 mm.

(1) The hydraulic piping system must be arranged so that it can always be switched between the main steering gears.

(2) Suitable equipment must be installed to keep the hydraulic fluid clean, taking into account the type and design of the transmission system.

2.4. Piping

(3) There must be equipment to vent air from the transmission system if necessary.

(2) Shall provide appropriate equipment to keep hydraulic fluid clean, taking into account the type and design of the drive system.

(3) Shall have equipment to vent air from the drive system if necessary.

(4) Safety valves must be installed at any part of the hydraulic system that can be isolated and generate pressure from energy sources or external forces. The set pressure of safety valves shall not be less than 1.25 times the maximum working pressure that may occur in the protected section. The minimum discharge rate of these safety valves shall not be less than the total output of the power pumps supplying the drive equipment increased by 10%. Under such conditions, the pressure increase shall not exceed 10% of the set pressure of the safety valve, and due attention shall be paid to the most difficult surrounding conditions anticipated for the viscosity of oil.

(5) Each reservoir containing hydraulic fluid must have a low-level alarm device to provide the earliest indication of fluid leakage. This alarm signal must be both audible and visual and transmitted to the control room and main machinery control position.

(6) Fixed reserve tanks must have sufficient capacity to replenish at least one drive system, including the working tank. The reserve tank must always be connected to the pipeline system so that the hydraulic system can be easily replenished from a location within the range of the hydraulic control room and must be equipped with a level gauge.

(7) For steering gear units arranged with two or more systems (energy supply systems or control systems) capable of operating simultaneously, precautions must be taken against hydraulic lock caused by a single failure. Each steering gear unit's hydraulic system must be equipped with relief valves to prevent this occurrence.

(8) It is not permitted to connect the piping system of the steering gear to another hydraulic system.

2.5. Restarting and loss of power alarm for steering gear

Main and auxiliary steering gears must:

(1) Be arranged to automatically restart when power is restored after a power loss, and

(2) Be capable of being started from a position in the control room. In the event of a power loss in any steering gear, audible and visual alarm signals must be sent to the control room.

2.6. Standby power source

When the diameter of the upper shaft of the rudder, as required in Section 2A, Part 2 of the Steel Hull Classification and Construction Regulations - QCVN 21: 2010/BGTVT, exceeds 230 mm, a backup power source meeting the following requirements must be provided:

(1) The backup power source must be:

(a) An emergency power source, or

(b) An independent power source placed in the steering gear compartment and used solely for this purpose.

(2) The backup power source must be able, within 45 seconds, to automatically supply replacement power to the steering gear and the control system connected to it and the rudder angle indicator. In this case, the backup power source must be able to provide sufficient power to the hydraulic steering gear to restore the specified steering capability as stated in 2.3(1). On vessels with GT of 10,000 or more, the backup power source must have a capacity sufficient to allow the steering equipment to operate continuously for at least 30 minutes, and on other vessels for at least 10 minutes.

(3) The automatic starting equipment for the generator or motor pump used as the independent power source specified in (1)(b) must meet the requirements for starting equipment and the characteristics of the emergency power generation station.

2.7. Electrical installation for hydraulic steering gear

(1) Cables in the electrical circuits as required by this Chapter must be double-cabled and separated throughout their length.

(2) Indicators showing which steering gears are in operation must be located in the control room and at the usual main machinery control position.

(3) Each electro-hydraulic steering gear with one or more steering gears must have at least two separate direct feed circuits from the main switchboard. However, one of these circuits may be fed through the emergency switchboard.

(4) Auxiliary electro-hydraulic steering gear linked to the main electro-hydraulic steering gear may be connected to one of the power supply circuits for the main steering gear. These circuits must have rated capacity sufficient to supply all motors that may be simultaneously connected to them and operate concurrently.

(5) Short-circuit protection devices and overload alarms must be provided for the circuits and motors. Overload alarm signals must be both audible and visible and must be located in positions easily seen at the usual main machinery control position and in the control room.

(6) Overcurrent protective devices, including starting currents if present, must withstand at least twice the full load current of the motor or circuit being protected and be arranged to permit suitable starting currents to pass.

(7) If three-phase power is used, an alarm device must be provided to indicate a fault in one of the phases of the power source. This alarm signal must be both audible and visual and located in a position easily seen, usually at the main machinery control position and in the control room.

(8) Alarm devices must include both sound and light and be located in the control room and at the main machinery control position. Audible signals must be maintained until acknowledged, and visual signals of each individual alarm must be maintained until the fault is rectified, at which point the alarm system must automatically reset to normal operation.

(9) If a vessel has a GT of less than 1,600 and auxiliary steering gear operated mechanically according to requirement 2.3(2), driven by non-electrical power or supplied by an electric motor primarily used for other purposes, then the main steering gear may be powered by a circuit from the main switchboard. If such an electric motor primarily used for other purposes is arranged to supply power to the auxiliary steering gear, the requirements from -5 to -7 may be waived by the Surveyor if the protective equipment and requirements in 2.5 and 1.11.1(3) applicable to the auxiliary steering gear are met.

(10) For vessels with a GT of less than 1,600 and hand-operated auxiliary steering gear, only one power supply circuit from the main switchboard for the main steering gear may be required.

2.8. Position of steering gear

(1) Steering gear must be located in a closed compartment that is easy to access and placed as far away from the engine room as possible.

(2) The steering gear compartment must be equipped appropriately to ensure access for work and control. Such equipment includes handrails on stairs and iron grating or non-slip surfaces to ensure suitable working conditions in the event of hydraulic fluid leakage.

(3) The engine room must have natural or forced ventilation measures to ensure that the temperature in the space where hydraulic equipment and electric motors operate does not exceed 45 ºC.

2.9. Communication means

There must be communication means between the control room and the engine room.

2.10. Rudder angle indicator device

The steering angle position measured in degrees must be:

(1) Indicated in the control room. The steering angle indicator device must be independent from the control system.

(2) Detectable in the engine room.

2.11. Control system

2.11.1. General requirements

1 The control system for the main steering gear must be equipped with:

(1) Main steering gear in both the control room and the engine room.

(2) Two independent systems if the main steering gear is arranged to meet requirement 2.1.3; both can be operated from the control room. In this case, it is not required to provide double steering wheels or tillers. If the control system has a remote hydraulic motor, then there is no need to install a second independent system.

(3) For auxiliary steering gear located in the engine room, if mechanically driven, it must be operable from the control room and independent from the control system of the main steering gear.

2 All control systems for main and auxiliary steering gears operable from the control room must comply with the following provisions:

(1) If controlled by electricity, there must be a separate electrical network supplied from a circuit of the steering gear from a point within the engine room, or directly from the busbar supplying power to the circuit of the steering gear at a point on the busbar adjacent to the power supply source for the circuit of the steering gear.

(2) In the engine room, there must be a means to disconnect any control system operable from the control room from the steering gear it serves.

(3) It must be possible to put the system into operation from a location in the control room.

(4) In the event of loss of power to the control system, there must be an audible and visual alarm signal in the control room.

(5) Only short-circuit protection devices must be provided for the circuits supplying the control system of the steering gear.

3 Cables and control systems that this standard requires to be duplicated should be placed as far apart as possible along their entire length.

4 For hydraulic steering gears arranged with two or more systems (energy systems or control systems) that can operate together, if a single failure causes a hydraulic lock that could lead to loss of steerage, an audible and visual alarm device must be installed on the bridge to identify the failed system.

5 When the hydraulic steering gear is automatically controlled, the automatic steering systems must comply with the following requirements:

(1) The bow direction of the vessel must be maintained at the set heading through coordination with a magnetic compass or an electronic compass.

(2) When the steering mode is switched from manual to automatic, the bow direction must be able to move towards the set heading.

(3) Operation must be easy and reliable.

(4) Apart from controlling the set heading action, any other control must not significantly affect the vessel's heading.

(5) The steering equipment must be a unified assembly to prevent unnecessary rudder movements that cause the vessel to deviate from its course.

(6) Automatic steering equipment status indicators must be provided.

(7) Limiting devices for the rudder angle and indicators showing that the rudder is approaching the preset limit angle must be provided.

(8) Audible and visual alarms must be issued in the control room when the bow direction deviates beyond the preset value.

(9) Audible and visual alarms must be issued in the control room to indicate power supply failures for the automatic steering and the alarm systems mentioned in Section 2.11.1.5(8).

(10) Control signals indicating the operating status (steering commands and responses) and the automatic steering mode must be connected and transmitted to the Voyage Data Recorder (VDR) for passenger ships and non-passenger ships with a total tonnage of 3000 GT or more.

2.11.2. Manual Override from Automatic Steering

Hydraulic steering gears of vessels with automatic control systems must be capable of quickly switching from automatic to manual steering.

2.12. Materials, construction, and durability of hydraulic steering gear

2.12.1. Materials

1 Materials used in hydraulic steering gears must be durable, free of defects, and suitable for operational conditions.

2 Materials for cylinders and casings of the rudder drive mechanism, high-pressure hydraulic pipes, and mechanical power transmission parts to the rudder shaft must not have a minimum elongation less than 12% and must not have a nominal tensile strength exceeding 650 MPa. This does not apply to materials for valves and bolts approved by the Classification Society.

3 Materials for rudder stocks and rudder arms must be forged or cast steel that meets the requirements of Part 7A of the Steel Hull Ship Classification and Construction Technical Regulations - National Technical Regulation - QCVN 21: 2010/BGTVT.

4 Materials for propellers and blades of the rudder drive mechanism with rotating blade type must be forged, cast, or spheroidal graphite iron that meets the requirements of Part 7A of the Steel Hull Ship Classification and Construction Technical Regulations - National Technical Regulation - QCVN 21: 2010/BGTVT.

5 Materials for bolts to assemble detachable rudder stocks and rudder arms and to fix blades to the propeller of the rudder drive mechanism with rotating blade type must be forged or rolled steel that meets the requirements of Part 7A of the Steel Hull Ship Classification and Construction Technical Regulations - National Technical Regulation - QCVN 21: 2010/BGTVT.

6 Other major components must meet recognized standards.

7 Materials different from those in -2 to -6 may be used if approved by the Classification Society.

2.12.2. Welding

1 All welds of the drive system components must be fully penetrated and free of harmful defects.

2 Welds in internal pressure-bearing parts of the mechanical drive system must have sufficient strength.

3 Welding must be performed according to welding procedures, welding materials (welding rods, welding wires, shielding gases), and welders certified by the Classification Society.

4 The quality of hydraulic steering gear welds must be inspected and tested using appropriate methods.

2.12.3. General Structure of the Rudder Drive System

1 The rudder drive system must have adequate strength and reliability.

2 The structure of the main components of the steering gear drive system must be determined to avoid stress concentration.

3 The design pressure for determining the size of pipes and other parts of the hydraulic pressure-bearing steering equipment must be at least 1.25 times the maximum working pressure that may occur under the conditions specified in 2.2(1), taking into account any low-pressure side pressures within the system. The design pressure shall not be less than the set pressure of the safety valve.

4 Particular attention must be given to the rationality of important parts that are not duplicated. When such important parts exist, anti-friction bearings such as ball bearings, roller bearings, or continuously lubricated sliding bearings or lubrication devices must be used.

5 Steel seamless pipes used in the hydraulic system of the steering gear must be made of alloy steel grade 3, grade 4 material (Part 7A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT) meeting the working conditions at high pressure or equivalent. If deemed necessary, fatigue calculations must be performed on the pipes and parts considering the dynamic loads caused by impact pressure. Both high-cycle fatigue and cumulative fatigue must be considered.

6 The cylinder support of the steering gear must be mounted on a base plate attached to the ship's hull with bolts and shims. The bolts must have sufficient strength and anti-loosening measures. The shims must be securely welded to the base plate and have sufficient strength to withstand the forces from the cylinders.

7 The base plate of the steering gear attached to the ship's hull must have a structure capable of bearing the forces exerted by the steering gear onto the hull. The feet of the base plate must be directly welded to the strong structure of the hull.

2.12.4. Strength of the steering gear drive equipment

1 In addition to the allowable stresses specified in this Standard, the strength of all parts of the steering gear drive equipment subjected to internal pressure must meet the corresponding requirements in Chapter 10, Part 3 of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT.

2 In the strength calculation specified in -1, the allowable stress for the main membrane stress shall not exceed the smaller value of (1) or (2) below:

(1)

(2)

Where:

 - The tensile strength limit of the material (MPa);

 - The nominal yield limit (conventional yield limit) of materials A and B given in Table 2.12.4 (MPa).

Table 2.12.4 - Values of A and B

2.12.5. Oil seals of the steering gear drive equipment

1 The oil seals between stationary parts forming part of the external pressure boundary must be metal-to-metal type or equivalent.

2 Hydraulic cylinders responsible for the steering gear drive equipment must be equipped with double seals at the sealing position with the piston rod, so that if one seal fails, it does not cause the steering gear drive system to stop functioning. Equivalent protective measures against oil leakage due to seal failure may be accepted (in the case of a dual cylinder actuator system, isolation of the failed cylinder may be applied).

2.12.6. Flexible hoses

Hose assemblies must be type-approved by the Survey Bureau and can be installed in places requiring flexibility and must meet the following requirements:

(1) The hoses shall not deform torsionally under normal operating conditions.

(2) Generally, flexible hoses must be limited to the necessary length to ensure flexibility and accurate operation of the machine.

(3) The hoses must be high-pressure hydraulic hoses suitable for the working conditions, i.e., compatible with the internal fluid, pressure, temperature, etc.

(4) The burst pressure of the hose shall not be less than four times the design pressure.

2.12.7. Steering wheel lever

1 The dimensions of the steering wheel lever, etc., made of rolled or cast steel, for transmitting force from the steering gear drive equipment to the steering shaft, must be determined so that the bending stress does not exceed 118/K (MPa) and the shear stress does not exceed 68/K (MPa) when the steering moment Tr acts.

Where:

T_R - The steering moment specified in 25.1.3, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT (Nm);

K - Material factor of the steering wheel lever specified in 25.1.1-2, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT.

2 Except for the requirements specified in -1, the dimensions of the Rapson slide type steering wheel lever or the piston type lever are determined according to the provisions from (1) to (4) as follows:

(1) The vertical cross-section through the centerline of the steering shaft on each side of the steering wheel lever pin must follow the formula below:

(D² - d²)H ≥ 170 T_RK

H/d ≥ 0.75

Where:

D - Outer diameter of the steering wheel lever pin (mm);

d - Inner diameter of the steering wheel lever pin (mm);

H - Height of the steering wheel lever pin (mm);

T_R - The steering moment specified in 25.1.3, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT (Nm);

K - Material factor of the steering wheel lever specified in 25.1.1-2, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT.

(2) The section modulus around the vertical axis must not be less than the value calculated by the following formula:

Z_TA = 11 T_RK

Where:

Z_TA - Section modulus defined around the vertical axis (mm³);

r - Distance from the steering shaft centerline to the section (mm);

R₁ - Length of the steering wheel lever arm measured from the steering shaft centerline to the point where the driving force is applied. In cases where this length changes with the rudder angle, R₁ is the maximum length within a 35° range of the rudder angle (mm);

T_R - The steering moment specified in 25.1.3, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT (Nm);

K - Material factor of the steering wheel lever specified in 25.1.1-2, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT.

(3) The area of the outer end section of the lever arm must not be less than the value calculated by the following formula:

Article 24_R18,5K

Where:

A_R - Defined area at the outer end of the lever arm (mm²);

R₂ - Length of the steering wheel lever arm measured from the steering shaft centerline to the point where the driving force is applied. In cases where this length changes with the rudder angle, R2 is the length when the rudder is at 0° (mm);

T_R - The steering moment specified in 25.1.3, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT (Nm);

K - Material factor of the steering wheel lever specified in 25.1.1-2, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT.

(4) In cases where two lever arms for the rudder are required, if the steering engines are connected to each arm and these two engines operate simultaneously, the size of the lever arm may be reduced from the size required under (2) and (3) to a level approved by the Registry.

3 Notwithstanding the requirements set forth in -1, the dimensions of the drive mechanism for the steel forged or cast paddle type rudder may be determined according to the following additional requirements supplementing those in 2.12.4.

(1) The dimensions of the paddle must meet the requirements set forth in -2(1).

(2) The modulus of the cross-sectional moment around the vertical axis and the area of the cross-section perpendicular to it shall not be less than the values calculated from the formulas below:

Z_v = 11 K

 

A_v  37 K

Where:

Z_v - The modulus of the bending moment section specified around the vertical axis (mm)³);

A_v The specified cross-sectional area of the blade (mm)²);

D - Outer diameter of the steering wheel lever pin (mm);

B - Height of the blade measured from the outer surface of the paddle (mm);

n - Number of blades;

T_R - The steering moment specified in 25.1.3, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT (Nm);

K - Material factor of the steering wheel lever specified in 25.1.1-2, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT.

4 Steering gears with two sections joined by bolts must have at least two bolts on each end. The diameter of the bolt threads shall not be less than the value calculated from the formula below. In this case, the thickness of the flange joint shall not be less than three-quarters the diameter of the bolts:

For coal-fired thermal power plants where the enterprise holds 100% of the registered capital and uses 100% of its own capital to invest in the project approved by the competent authority, E is determined as 100%;_b1,45K

Where:

For coal-fired thermal power plants where the enterprise holds 100% of the registered capital and uses 100% of its own capital to invest in the project approved by the competent authority, E is determined as 100%;_b - Required diameter of the bolt threads (mm);

T_R - The steering moment specified in 25.1.3, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulations - QCVN 21: 2010/BGTVT (Nm);

K - Material factor for the steering gear specified in 25.1.1-2, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulation - QCVN 21: 2010/BGTVT;

n - Number of bolts at each end;

b - Distance from the center of the steering shaft to the center of the bolt (cm).

5 The steering gear must be securely fastened to the rudder shaft using key joints, shrink fitting, or bolts. However, it may be installed without key joints if the assembly method is approved by the Registry.

6 The dimensions of the drive mechanism for the cast iron paddle type rudder must be determined so that it does not exceed a bending stress of 94/K (MPa) or a shear stress of 54/K (MPa) under the effect of the rudder torque T._RAlternatively, the dimensions can be calculated according to the requirements set forth in -3 and increasing the specified rudder torque Tr specified in 25.1.3, Part 2A of the Classification and Construction Rules for Steel Hull Ships - National Technical Regulation - QCVN 21: 2010/BGTVT by 1.2 times for calculation purposes.

2.12.8. Rudder stop devices

1 Steering gears must have rudder stop devices to securely hold the rudder in place in case of failure.

2 Hydraulic steering engines must have active devices such as limit switches to stop the engine before the rudder reaches the stop position. These devices must be synchronized with the main engine and not synchronized with the control system of the steering engine. However, these devices may operate through mechanical linkages such as levers.

3 There must be a brake or suitable cable for the steering gear to securely hold the rudder in place in case of failure. In the case of hydraulic steering, if the rudder can be safely stopped by closing the oil pressure valves, this requirement is not necessary.

2.13. Additional requirements for liquid cargo ships, liquefied gas carriers, and chemical tankers with GT of 10,000 or more and other ships with GT of 70,000 or more. Liquid cargo ships, liquefied gas carriers, and chemical tankers with GT of 10,000 or more and other ships with GT of 70,000 or more.

2.13.1. Main steering gear

1 For liquid cargo ships, liquefied gas carriers, or chemical tankers with GT of 10,000 or more and all other ships with GT of 70,000 or more, the main steering engine must have two identical hydraulic steering engines meeting the requirements of Clause 2.1.3 of this standard.

2 The steering gear on liquid cargo ships, liquefied gas carriers, or chemical tankers with GT of 10,000 or more must meet the following requirements:

(1) The main steering gear must be arranged so that in the event of loss of steering due to malfunction in any part of the main steering gear drive system, except for failures in the steering gear motor, steering gear lever, or jamming in the rudder drive mechanism, steering capability must be restored within 45 seconds after the loss of one drive system.

(2) The main steering gear must include:

(a) Two independent and separate rudder drive systems, each of which must be able to meet the requirements of Clause 2.2(1) of this standard or:

(b) At least two similar rudder drive systems operating simultaneously in normal mode must be capable of meeting the requirements of Clause 2.2(1) of this standard. In this case, the following additional requirements must also be met:

(i) Detection of hydraulic fluid loss in one system and automatic isolation of the faulty system to allow the remaining systems to continue full operation.

(ii) When necessary to achieve steering capability, the mechanical-hydraulic drive systems must be interconnected.

2.13.2. Control

For liquid cargo ships, liquefied gas carriers, or chemical tankers with GT of 10,000 or more, the exemption for remote hydraulic control motors allowed in 2.11.1-1 (2) shall not apply.

2.13.3. Quantity and durability of the rudder drive mechanism

1 For liquid cargo ships, liquefied gas carriers, or chemical tankers with GT of 10,000 or more but with total deadweight under 100,000 tons, only one rudder drive mechanism is permitted, provided that:

(1) After losing steering capability due to malfunction of any part of the pipe system or in one of the steering engines, steering capability must be restored within 45 seconds.

(2) Separate consideration must be given to fatigue and corresponding mechanical failure calculations for the design including installation of sealing equipment, testing, inspection, and effective maintenance. In this case, high cycle fatigue and cumulative fatigue must also be considered.

(3) Isolation valves must be directly mounted on the rudder drive mechanism to isolate the rudder drive mechanism from hydraulic oil in the pipe systems, and

(4) Safety valves must be installed to protect the rudder drive mechanism from overpressure as required in Clause 2.4(4).

2 For liquid cargo ships, liquefied gas carriers, or chemical tankers with GT of 10,000 or more but with total deadweight under 100,000 tons and having only one rudder drive mechanism, in addition to the durability requirements in 2.12.4, the rudder drive mechanism must meet the following additional requirements:

(1) Detailed calculations must be performed for the important parts of the steering gear drive system to confirm their durability.

(2) Detailed stress calculations must be carried out for the parts of the steering gear drive system subjected to hydraulic pressure to confirm that they are sufficiently durable to withstand design pressure.

(3) Due to the complexity of the design or production process, fatigue analysis and mechanical failure analysis must be conducted when necessary. In such cases, high cycle fatigue and cumulative fatigue must be considered. All anticipated dynamic loads related to these analyses must also be taken into account. If necessary, the Registry may require experimental stress analysis to supplement or replace theoretical design.

(4) To determine the general dimensions of the parts of the steering gear drive systems subjected to internal hydraulic pressure, allowable stresses shall not exceed:

Terrestrial Mobile Radio Equipment with Detachable Antennas Used for Analog Voice Communication ≤ f

(b) ≤ 1,5 f

(c) ≤ 1,5 f

(d)  + ≤ 1,5 f

(e) + ≤ 1,5 f

Where:

- The equivalent membrane stress (MPa);

 - The local equivalent membrane stress (MPa);

 - The equivalent bending stress (MPa);

f - The smaller value of /A or /B;

 - The tensile strength limit of the material (MPa);

 - The smallest nominal yield strength or the specified yield strength of the material (MPa) A and B are given in the table below:

Table 2.13.3.1 - Values of A and B

"5. The pre-tax weighted average cost of capital i (%) is determined according to the formula below:_b = PA

Where:

"5. The pre-tax weighted average cost of capital i (%) is determined according to the formula below:_b - The smallest burst pressure (MPa);

P - Design pressure (MPa);

A - As in (4);

 - The actual tensile strength of the material (MPa);

 - The smallest nominal tensile strength of the material (MPa).

2.14. Certain specific requirements for hydraulic steering gear used on inland waterway vessels with restricted operational areas

2.14.1. Hydraulic steering gear used on inland waterway vessels under 500 GT classified for operation in Restricted Sea Area II or equivalent which does not operate on international routes need not comply with the requirements set forth in section

(1) The requirements stipulated in 2.11.1.4 need not be applied;

(2) The requirements at 2.5 need not be applied;

(3) The requirements prescribed in 2.4(5) and the requirements concerning the steering gear prescribed in the last part of 2.4(6) need not be applied (except where suitable auxiliary steering gear is not required according to the requirements at 2.1.3);

(4) The requirements regarding standby power supply prescribed in 2.6 need not be applied;

(5) The requirements at 2.7(1) and (7) need not be applied;

(6) The requirements concerning overload protection for electrical circuits and motors prescribed in 2.7(5) need not be applied;

(7) The means of communication between the bridge and the steering gear compartment prescribed in 2.9 may be replaced by an appropriate alternative means;

(8) The requirements at 2.11.1(3) need not be applied.

2.14.2. Vessels marked with restricted ship classification "Restricted III" or equivalent

For vessels with a rudder stock diameter above less than 120 mm according to 25.1, Part 2A of the Rules for Classification and Construction of Steel Hull Ships - National Technical Regulation - QCVN 21: 2010/BGTVT (calculated with material factor K_{"7. A flexible power plant is a thermal power plant using reciprocating internal combustion engines (RICE) or aeroderivative gas turbines (Aero-GT) with fast start-up capabilities, designed in modular form to generate electricity for balancing capacity and maintaining power system stability."} (3) Be designed so as not to fail when reversing at maximum speed. However, this design requirement does not need to be proven through testing at maximum reverse speed and at the largest rudder angle._{"7. A flexible power plant is a thermal power plant using reciprocating internal combustion engines (RICE) or aeroderivative gas turbines (Aero-GT) with fast start-up capabilities, designed in modular form to generate electricity for balancing capacity and maintaining power system stability."} less than 1), the requirement for auxiliary steering gear prescribed in 2.12 may be waived if spare parts for replaceable components such as seals and bearings are provided for the main mechanical steering gear and reserve steering cables are provided for the manually operated main steering gear.

2.15. Hydraulic steering gear on inland waterway vessels

2.15.1. Certain specific requirements for hydraulic steering gear on inland waterway vessels are as follows:

(1) Hydraulic steering gear on inland waterway vessels shall comply with the provisions set forth in section 2.14;

(2) Auxiliary steering gear must have the capability to turn the rudder from 15° port to 15° starboard within 60 seconds when the vessel is fully loaded and moving forward at either the design speed or 6 km/h, whichever is greater.

2.15.2. The structure connecting to the rudder shaft of the steering gear drive system must prevent damage when the rudder shaft moves along its axis within the permitted range, up to a maximum of 0.1 d (d - the upper rudder stock diameter).

3. MANAGEMENT PROVISIONS

3.1. The hydraulic steering gear and its components must be inspected, certified during production, manufacture, importation, repair, and operation in accordance with relevant legal regulations, standards, and guidelines of this standard. The design must be reviewed and certified by the Registry.

3.2. The design basis, manufacturing facilities, testing facilities for hydraulic steering gear, and personnel of these facilities must have adequate capacity and be evaluated and certified by the Registry. Testing, inspection, and measurement equipment of these facilities must be periodically calibrated by the Registry.

3.3. Hydraulic steering gear must be approved and type-approved by the Registry.

3.4. The quality of welds and materials used in the manufacture of hydraulic steering gear must be inspected using non-destructive testing (NDT) or destructive methods by qualified welders and inspectors certified by the Vietnam Registry of Shipping in accordance with corresponding standards and regulations.

3.5. Imported hydraulic steering gear

Imported hydraulic steering gear and components used in the manufacture of hydraulic steering gear must be inspected and certified by the Vietnam Registry of Shipping to comply with the requirements of this standard and relevant technical standards and legal regulations concerning quality assurance, technical safety, and environmental protection.

3.6. Regulations on inspection and testing of hydraulic steering gear

3.6.1. Hydraulic steering gear and accompanying parts must be tested at facilities with sufficient capacity to perform such tests.

3.6.2. In addition to the testing requirements stipulated in this standard, hydraulic equipment and piping systems must meet the requirements of 10.9, 12.6, 13.17 - Part 3 of the Rules for Classification and Construction of Steel Hull Ships - National Technical Regulation - QCVN 21: 2010/BGTVT. All pressurized parts must undergo pressure testing at 1.5 times the design pressure.

3.7. Testing methods

3.7.1. Pre-test inspection

3.7.1.1.Review design documentation, test procedures, acceptance records of manufactured components, and internal test records.

3.7.1.2. Verify the compatibility of installed hydraulic and electrical equipment on the steering gear with existing certificates.

3.7.1.3. Verify the structural compliance of the steering gear with the approved design.

3.7.1.4. Inspect the installation of the steering gear on the test bed and the readiness of the manufacturing facility for testing.

3.7.1.5 Conduct a hydraulic pressure test on the pipeline and equipment with a test pressure equal to 1.5 times the maximum working pressure.

3.7.2. Operation Test

3.7.2.1. Test the operation of the electrical indication system

Test the indicator lights, V meters, A meters, etc.

3.7.2.2. Test the operation of the control electrical system

Test the control lock function of the steering station at the engine room control panel;

Test the start-up of each pump at the steering station and the engine room. Check the interlock switch (if present);

Test the electric solenoid valve control at the steering station and the engine room. Check the interlock function of these valves; Test the ability to automatically restart when power is restored after loss.

3.7.2.3. Test the operation of the rudder angle indication system

Check the accuracy of the rudder angle indicator meter;

Check the anti-vibration and anti-loosening capability of the rudder angle transmitter mechanism.

3.7.2.4. Test the operation of the alarm circuit

Test for low oil level in the tank;

Test for overload;

Test for phase loss;

Test for loss of control power supply;

Test the readiness status of the alarm bells, horns, and indicator lights.

3.7.2.5. Test the unloaded operation of the steering gear

Test the switching operation between different steering gears;

Check the stable operation of each steering gear during continuous rudder turning operations;

Check the sensitivity of the control system when performing small movements (up to 10 degrees), continuous reverse movements;

Measure the rudder turning time of each steering gear according to regulations with the main steering gear (t/650) and auxiliary steering gear (t/300);

Test the manual steering gear's rudder turning capability in case of emergency (if present);

The test results are recorded in the Test Report at the workshop for the hydraulic steering gear.

3.7.3. Load Test with Hydraulic Pump and Electric Motor

The hydraulic pump and electric motor must be tested according to the following items:

1. Operation Test

2. Overload Test

3. Stability Work Test

3.7.3.1. Testing Methods and Arrangements

a) Testing Arrangement

The hydraulic pump and electric motor of the steering gear can be tested using its own power unit. Measuring devices are connected to the power unit according to the diagram in Figure 1.

b) Operational testing

The operation test with the hydraulic pump must be conducted at 100% design capacity.

Run the hydraulic pump unloaded for 15 minutes, determine the parameters of the hydraulic pump and electric motor.

Adjust the load relief valve, increase the hydraulic pump discharge pressure to 50%, 75%, and 100% of the maximum working pressure of the steering gear (P_max).

At 100% P_max the testing duration shall not be less than 30 seconds. Determine the parameters of the hydraulic pump and electric motor.

c) Overload Test

Increase the hydraulic pump discharge pressure to 115% P_max for a period of (10-13) seconds. Determine the parameters of the hydraulic pump and electric motor.

d) Stability Work Test

After the above tests, the hydraulic pump must undergo a long-term endurance test lasting 30 minutes. The hydraulic pump discharge pressure needs to be maintained at a level suitable for the long-term operating capacity (100% capacity) of the electric motor.

 

3.7.3.2. Parameters to be determined during the test

Speed

Capacity of the hydraulic pump

Discharge pressure

Current intensity, voltage of the electric motor

Oil temperature

3.7.3.3. Check in open state

During the testing process, if any abnormal conditions such as excessive noise, high oil temperature, etc., occur, the hydraulic pump must be checked in an open state to find the cause. If the hydraulic pump has manufacturing defects, it must be removed.

3.7.3.4 Prepare the test report

The results of the inspection and testing of the hydraulic pumps and electric motors used for the steering gear are reflected in the Workshop Test Report for the hydraulic pumps and electric motors.

3.8. Factory testing for hydraulic steering gears used in liquid cargo ships, liquefied gas carriers, and chemical tankers with GT from 10,000 tons and other ships with GT from 70,000 tons

For liquid cargo ships, liquefied gas carriers, or chemical tankers with GT from 10,000 tons but with total deadweight under 100,000 tons and only one steering gear drive device, this steering gear drive device must be fully and appropriately tested using non-destructive testing methods to detect both surface and internal defects. The procedures and standards accepted for non-destructive testing will be reviewed by the Registration Authority for each case. When deemed necessary, mechanical destructive analysis methods must be used to determine the maximum allowable defect size.

3.9. Record Issuance Regulations

The Vietnam Registration Authority issues, prints, guides, prepares, and issues certificates and forms related to the inspection and certification of hydraulic steering gears according to the provisions of this Standard.

3.9.1. Inspection Request

The inspection request is sent by organizations, entities, or individuals involved in the design, manufacture, repair, modification, import, operation, and use of hydraulic steering gears to the Vietnam Registration Authority.

3.9.2. Certificate

3.9.2.1. The Vietnam Registration Authority will issue corresponding Certificates as stipulated in Sections 3.1, 3.2, 3.3, 3.4, and 3.5 of Part 3 of this Standard.

3.9.2.2 The issued certificate will become invalid in the following cases:

(a) If any requirement of the Standard is missing or;

(b) Not inspected according to the regulations or;

(c) Exceeded the inspection validity period or;

(d) The actual equipment no longer complies with the issued certificate or

(e) After an accident or cancellation.

3.9.2.3. Reissuing Certificates

The Vietnam Registration Authority will reissue the Certificate after the equipment has been inspected, tested, and provided with a corresponding inspection report in accordance with the provisions of this Standard.

3.9.3. Inspection Report

After completing the inspection and testing of hydraulic steering gears and their components, the Vietnam Registration Authority will prepare an inspection report corresponding to the type of inspection specified in this Standard;

4. RESPONSIBILITIES OF ORGANIZATIONS AND INDIVIDUALS

4.1. Organizations, entities, and individuals involved in the production, manufacture, import, design, operation, use, management, inspection, technical safety certification, and environmental protection of hydraulic steering gears must comply with the provisions of this Standard and relevant laws, regulations, and guidelines, and bear responsibility for the inspection results.

4.2. Responsibility of the design entity

Adhere to the technical requirements of this Standard.

4.3. Responsibility of the organization or individual importing, the manufacturer, and the testing facility for hydraulic steering gears

1 Comply with current technical regulations, standards, and specifications when manufacturing, assembling, repairing, modifying, and importing hydraulic steering gears.

2 Establish technological processes, conduct quality inspections and tests, invest in appropriate inspection and testing equipment; inspection equipment must be periodically calibrated; organize quality inspections for each product and bear responsibility for the quality of products leaving the factory.

3. Bear responsibility for the origin, place of manufacture, and quality of imported hydraulic steering machines.

4.4. Responsibilities of organizations and individuals using hydraulic steering machines

Be responsible for repairing and maintaining hydraulic steering machines to ensure technical safety standards and environmental protection between two inspection periods conducted by the registration inspection unit to maintain the technical condition of the hydraulic steering machines in accordance with the provisions of this Standard.

4.5. Organizations and individuals importing, manufacturing facilities, testing facilities, and equipment owners must preserve and maintain, and not repair or erase inspection result confirmation papers, certificates that have been issued, and present them when requested by authorized enforcement officers.

Chapter 5. ORGANIZATION OF IMPLEMENTATION

5.1. The Vietnam Registration Inspection Authority has the responsibility to implement, guide, and enforce this Standard; advise and propose the Ministry of Transport to amend and supplement this Standard in a timely manner when necessary.

5.2. Based on actual conditions when implementing this Standard, the Vietnam Registration Inspection Authority has the responsibility to advise and propose the Ministry of Transport to amend and supplement this Standard in a timely manner.

5.3. When referenced standards or guidelines specified in this Standard are changed, supplemented, or replaced, they shall be implemented according to the content of the new document.