SY/T 4128-2024 Code for integral PWHT construction of large-scaleequipment by internal combustion method English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
E
Professional standard of the People's Republic of China
SY/T 4128-2024
Replaces SY/T 4128-2014
Code for integral PWHT construction of large-scale equipment by internal combustion method
大型设备内燃法整体焊后热处理施工规范
(English Translation)
Issue date: 2024-12-25 Implementation date: 2025-06-25
Issued by National Development and Reform Commission, P.R.C
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 General Principles
5 Design
5.1 Installation Principles
5.2 Materials
5.3 Tank Venting Design
5.4 Floating Roof Seal Design
5.5 Floating Roof Drain Design
5.6 Other Attachments
6 PV Valve
6.1 Structure
6.2 Specification, Model, and Set Pressure Grade
6.3 Materials
6.4 Technical Requirements
6.5 Manufacturing
6.6 Inspection and Testing
6.7 Marking
7 Open Vent
7.1 Structure
7.2 Materials
7.3 Technical Requirements
7.4 Manufacturing
7.5 Marking
8 Automatic Bleeder Vent
8.1 Structure and Specification
8.2 Materials
8.3 Technical Requirements
8.4 Marking
9 Gravity Emergency Relief Valve
9.1 Structure and Specification
9.2 Materials
9.3 Technical Requirements
9.4 Inspection and Testing
9.5 Marking
10 Primary Seal Device
10.1 Structure
10.2 Materials and Specifications
10.3 Technical Requirements
10.4 Marking
11 Secondary Seal Device
11.1 Structure
11.2 Materials and Specifications
11.3 Technical Requirements
11.4 Marking
12 Eliminated Oil&Gas Space Seal Device
12.1 Structure
12.2 Materials and Specifications
12.3 Technical Requirements
12.4 Marking
13 Floating Roof Drain Device
13.1 Structure
13.2 Materials
13.3 Technical Requirements
13.4 Inspection and Testing
13.5 Marking
14 Emergency Drain Device
14.1 Structure
14.2 Materials
14.3 Technical Requirements
14.4 Inspection and Testing
14.5 Marking
15 Weight-Type Wax Scraper Device
15.1 Structure
15.2 Materials
15.3 Technical Requirements
15.4 Manufacturing, Installation and Inspection
15.5 Marking
16 Water Hammer Prevention Heater
16.1 Structure
16.2 Technical Requirements
16.3 Installation
16.4 Marking
17 Gauging Hatch
17.1 Structure and Specification
17.2 Materials
17.3 Technical Requirements
17.4 Marking
18 Packaging and Transport
Appendix A (Normative) Properties of Rubber Materials for Seals
Appendix B (Normative) Properties of Foam Materials for Seals
Appendix C (Normative) Simplified Calculation Method for Venting Capacity
C.1 Scope of Application
C.2 Calculation Method
Appendix D (Normative) Test for Venting Devices
D.1 General Provisions
D.2 Test Apparatus
D.3 Test Method
D.4 Method for Determining Venting Capacity
D.5 Pressure Test of Valve Body
Appendix E (Informative) Calculation Example of Compression Force for Counterweight Force Mechanism
E.1 Given Conditions
E.2 Compression Force Calculation
1 General Provisions
1.0.1 This code is formulated to standardize the technical requirements for integral post-weld heat treatment of large field-assembled equipment using the internal combustion method and to ensure the quality of post-weld heat treatment.
1.0.2 This code applies to the integral post-weld heat treatment of large equipment such as spherical storage tanks, towers, and reactors fabricated and assembled on-site using the internal combustion method.
1.0.3 In addition to complying with this code, the on-site integral post-weld heat treatment of large equipment using the internal combustion method shall also comply with current relevant national standards.
2 Terms and Symbols
2.1 Terms
2.1.1 internal combustion method
A method of heating equipment using high-temperature flue gas generated by flame as the heat source, through convection, thermal radiation, or heat conduction inside the equipment.
2.1.2 holding temperature
The specified temperature range maintained for the necessary duration during post-weld heat treatment of the equipment to achieve its purpose.
2.1.3 holding time
The duration during which the equipment being heat treated is maintained at the holding temperature.
Note: The holding time is calculated from the moment when the temperature at all temperature measurement points reaches the minimum holding temperature until the moment when the temperature at any measurement point falls below the minimum holding temperature.
2.2 Symbols
PWHT — Post Weld Heat Treatment, referred to as heat treatment;
δPWHT — Thickness for post-weld heat treatment.
3 Basic Requirements
3.1 Personnel
3.1.1 Technical and quality personnel engaged in heat treatment shall possess certain professional theoretical knowledge and practical experience.
3.1.2 Heat treatment operators shall undergo professional training and assessment before taking up their posts, and shall be familiar with and master the post-weld heat treatment procedure specifications for large equipment.
3.1.3 Special operation personnel shall hold a valid "Special Operation Certificate" issued by the relevant authority.
3.1.4 Personnel involved in heat treatment-related operations shall receive relevant safety education and comply with the safety operation procedures for their respective positions.
3.2 Environment
3.2.1 Before heat treatment operations, measures shall be taken against wind, rain, snow, and lightning based on the on-site weather conditions. Operations shall be prohibited when effective protective measures are not in place.
3.2.2 During the heat treatment process, operations shall be stopped under any of the following conditions:
1 Heavy snow, moderate rain or heavier;
2 Wind speed of 10.8 m/s or higher.
3.2.3 Records shall be kept of meteorological conditions during heat treatment work, such as temperature, wind speed, and weather conditions.
4 Heat Treatment System
4.1 General Provisions
4.1.1 The heat treatment system shall include heating, temperature control and measurement, insulation, and smoke exhaust systems, and shall meet the requirements of the heat treatment process.
4.1.2 Heat treatment shall not cause problems such as excessive oxidation or corrosion on the equipment surface.
4.1.3 The heating system shall ensure uniform heating of the equipment being treated.
4.1.4 The temperature measurement and control system shall accurately measure, feedback, and control the temperature.
4.1.5 The accuracy class of instruments such as pressure gauges and flow meters shall not be lower than Class 2.5, and the accuracy class of temperature gauges shall not be lower than Class 0.5.
4.1.6 Measuring instruments and devices shall be verified or calibrated and used within their validity period.
4.1.7 The fuel, insulation materials, and instruments used in the heat treatment system shall comply with the provisions of current relevant national standards.
4.2 Heating System
4.2.1 The heating system includes burners, fuel storage devices, and fuel delivery pipelines. It shall be capable of providing continuous heat supply and shall be adjustable to control the heat output.
4.2.2 The power of the burner and the amount of heat treatment fuel shall be selected based on thermal calculations. The power of the burner shall not be less than 1.5 times the calculated value of heat required for heat treatment. Thermal calculations may be performed according to the provisions in Appendix A of this code.
4.2.3 Gas fuel should be preferred for heat treatment of large towers and reactors, while liquid fuel should be preferred for heat treatment of spherical storage tanks. The sulfur content of the heat treatment fuel shall comply with the provisions of current relevant national standards. The sulfur content in gas fuel shall be lower than 0.57 g/m³, and the sulfur content in liquid fuel shall be lower than 0.5%.
4.2.4 The location of the fuel storage device shall be kept away from ignition sources, with a distance not less than 10 m. A flame arrester shall be installed on the fuel pipeline between the fuel storage device and the heating device. Fuel pipelines shall be laid naturally, shall not bear weight, and shall not be close to high-temperature pipelines or equipment.
4.2.5 Heating compensation devices shall be installed at locations where the heat treatment temperature is likely to be low, such as sudden changes in equipment structural dimensions, product test coupons, and local reinforcement plates.
4.3 Temperature Control and Measurement System
4.3.1 The temperature control and measurement system includes the temperature control system, recorder, thermocouples, and compensation wires.
4.3.2 The temperature control system shall have automatic temperature control functionality.
4.3.3 Thermocouples shall comply with the relevant provisions of the current national standard "Thermocouples — Part 1: EMF specifications and tolerances" GB/T 16839.1.
4.3.4 Thermocouples shall be matched with compensation wires, the temperature control system, and the recorder. Thermocouples shall be connected to the equipment being heat treated using capacitive energy storage spot welding or slotted nuts to ensure firm fixation.
4.3.5 After removing thermocouples, the weld points shall be ground smooth. The base material shall not be damaged during grinding.
4.3.6 Temperature measurement points shall be evenly arranged on the external surface of the equipment. The spacing between adjacent measurement points shall not exceed 4500 mm. Measurement points shall also be arranged at locations prone to temperature changes, such as air inlets, flue outlets, sudden changes in equipment structural dimensions, and on product test coupons. A layout drawing of the temperature measurement points shall be prepared.
4.3.7 Compensation wires shall comply with the relevant provisions of the current national standard "Compensating cables for thermocouples" GB/T 4989. Compensation wires shall be connected to thermocouples and the control instrument ensuring correct polarity matching.
4.3.8 The temperature recorder shall have a continuous automatic recording function, and a portable thermometer shall be provided for temperature monitoring.
4.4 Insulation System
4.4.1 Insulation materials shall have quality certification documents and shall meet relevant health, safety, and environmental requirements. During heat treatment, insulation materials shall be reasonably selected based on the heat treatment temperature and process, material density, and thermal conductivity. Aluminum silicate materials should be preferred for insulation.
4.4.2 The insulation layer thickness shall be determined based on thermal calculations and shall not be less than 100 mm.
4.4.3 The insulation layer shall fit tightly against the equipment surface, have uniform thickness without holes, and shall not detach during the entire heat treatment process. The insulation layer shall be laid in layers. The overlap length between two adjacent insulation blocks in each layer shall not be less than 100 mm. The splicing joints of the inner and outer insulation layers shall be staggered by at least 100 mm.
