GB 40881-2021Code for security system design of low concentration gas pipeline transportation of coal mine (English PDF)

1 Scope

GB 40881-2021 is the Chinese national standard on code for security system design of low concentration gas pipeline transportation of coal mine, in the field of environment and health protection, safety. It carries no /T suffix, which in the Chinese system means compliance is mandatory: a product or a practice within its scope has to meet it to be lawfully made, sold or carried out in China. It was issued on 11 October 2021 by the State Administration for Market Regulation; Standardization Administration of China, and has been in force since 1 May 2022. Classification: ICS 13.100, CCS D09. This page is published from the official record of the standard held by the Chinese standards administration: the identification, the dates, the classification and the issuing body are taken from there. The clause text, the tables and the numeric limits are in the document itself, which is delivered complete in English translation.

This document specifies the basic requirements for the design of the security system for low concentration gas pipeline transportation of coal mine, the installation requirements for security facilities. This document is applicable to the security system design of low concentration gas pipeline transportation of coal mine.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB 50016, Code for Fire Protection Design of Buildings

GB 50028, Code for design of city gas engineering

GB 50057, Code for design protection of structures against lightning

GB 50471, Code for design of the gas drainage engineering of coal mine AQ 1072, Specification for water sealing of fire barriering and explosion venting devices of gas pipeline transportation AQ 1073, Specification for automatic preventing explosion devices of gas piping AQ 1078, General specifications for transmission system of low concentration coal mine gas blending with water mist AQ 1079, General specification for automatic spurting powder explosion suppression devices of gas pipeline transmission AQ/T 1104, Technical Rules for the Security Delivery Device of Gas-water Two- phase Flow of Low Concentration Gas in Coal Mine CJJ 33, Code for construction and acceptance of city and town gas distribution works A device that the continuous mixing of gas and fine water mist in the coal mine gas pipeline can inhibit the flame propagation of combustion or explosion.

4 Basic requirements

4.1 In the low concentration gas pipeline transportation of coal mine, close to the possible fire source points (generator set intake side, ground emptying nozzle, spontaneous combustion and easy spontaneous combustion coal seam gob drainage gas pipe inlet), a security system shall be installed to ensure the security of pipeline transportation.

4.2 The system design shall follow the basic principles of "fire and explosion prevention, explosion suppression and explosion prevention, multi-level protection, and security assurance". The security system shall choose different combinations of security facilities such as fire and explosion relief, explosion suppression, explosion prevention, anti-backflow, security monitoring and control, and lightning protection according to the different uses of gas transportation.

4.3 Anti-backflow devices shall be installed in the positive pressure pipeline system. Prevent backflow due to sudden shutdown of the extraction pump.

4.4 Buffer tanks shall not be installed in low concentration gas pipeline transportation systems.

4.5 Pressurization equipment shall choose a wet compressor.

4.6 Drainage equipment shall choose wet drainage pumps.

4.7 When conveying under positive pressure, the conveying pressure shall not exceed 20kPa.

4.8 There shall be no mechanical moving parts and electrical components in the dehydrator.

4.9 Security monitoring and control facilities shall be set up in the pipeline transportation system. In addition to complying with the relevant provisions of MT209, security monitoring and control facilities shall also have the following functions:

a) The function of state parameter monitoring and alarm of gas pipeline transportation security facilities;

b) In the event of gas combustion or explosion, it shall be possible to control the rapid start-up of security equipment. Control gas combustion or explosion within a certain range.

4.10 The pipelines and accessories in the security facility installation section shall be 6 - Water sealing of fire barriering & explosion venting device; 7 - Pressure sensor; 8 - Flame sensor; 9 - Power equipment; 10 - Branch pipe; 11 - Airflow direction. Figure 1 -- Schematic diagram of installation of security facilities for gas power generation utilization system

5.1.3 Flame and pressure sensors for monitoring are installed on the branch pipe. The flame sensor is no more than 3m away from the generator set. The pressure sensor is 3m~5m away from the flame sensor. If a dehydrator is installed on the branch pipe, the flame sensor is located between the dehydrator and the generator set, 2m~3m away from the dehydrator. The pressure sensor is located between the dehydrator and the branch pipe, 1m~2m away from the dehydrator.

5.1.4 The distance between the installation position of the water sealing of fire barriering & explosion venting device and the farthest branch pipe (along the pipeline axis) shall be less than 30m.

5 Security facilities...

6 Others

6.1 Gas pumping stations, gas transmission station buildings and exhaust pipes shall comply with the requirements of GB 50057. Set up lightning protection facilities. Install lightning protection belt or lightning rod device, respectively. The drainage pipeline leading to the underground shall comply with the requirements of GB 50471. Take lightning protection and isolation measures.

6.2 Ground gas transmission pipelines shall be laid underground. When overhead laying is required in special circumstances, grounding shall be done every 25m within 100m of the pipeline entering and leaving the building. Its grounding resistance shall not be greater than 20Omega.