GB27791-2020
City gas pressure regulating installation
城镇燃气调压箱
GB 27791-2020 is a current mandatory Chinese national standard for City gas pressure regulating installation. It appears in the Construction compliance cluster with a product safety focus and has an implementation date of Dec 1, 2021.
Applicability depends on product scope, certification route, competent authority notices and transition rules. Requst for the translation or verify source before using this record in a compliance decision.
Compliance overview
Scope and applicability
GB 27791-2020 applies to city gas pressure regulating installations (also known as gas pressure regulating boxes) used in urban gas distribution systems. The standard covers installations with a maximum inlet working pressure not exceeding 10.0 MPa and operating temperatures ranging from greater than -20°C to less than or equal to 60°C. This standard does not apply to underground gas pressure regulating installations. It is relevant for manufacturers and engineers involved in the design, production, and testing of gas pressure regulating equipment for the Chinese market, including components such as regulators, filters, safety devices, valves, and metering systems.
Technical requirements
The standard specifies comprehensive requirements for the structure and materials of gas pressure regulating installations. This includes general design requirements for the box body, piping components, valves, metering systems, heating equipment, electrical and instrumentation systems, and safety configurations. The box body must be constructed with fire-resistant materials rated at B1 level per GB 8624, and must include explosion relief ports and natural ventilation openings sized according to gas relative density. All pressure-bearing components must meet minimum wall thickness and material grade requirements based on design pressure levels. Key performance requirements include strength testing where components must withstand 1.5 times design pressure (minimum 0.6 MPa for water medium) without leakage, deformation, or abnormal sounds. Gas tightness testing requires the entire piping system to be leak-free under design pressure conditions. The standard also specifies outlet pressure setting error limits of ±5% of the set value, and safety device activation pressure setting errors not exceeding ±5% of the set value, with additional tiered limits based on outlet pressure ranges. The standard mandates non-destructive testing (NDT) of welded joints on pressure-bearing components, with testing methods including radiographic, ultrasonic, magnetic particle, and penetrant testing. NDT requirements vary by design pressure and weld joint classification (A, B, C, D categories), with 100% testing required for higher-pressure applications and sampling-based testing for lower-pressure ranges. Welded joints that fail NDT may be repaired a maximum of two times per joint. Additional requirements cover rated flow verification (measured value must not be less than declared value), shut-off pressure compliance, and insulation performance where insulating flanges or joints must maintain insulation resistance greater than 20 MΩ per SY/T 0516 specifications.
Testing methods
The standard defines testing procedures using calibrated instruments with specified accuracy levels. Key tests include: Strength testing using water (or gas under specific conditions) with gradual pressurization and minimum 30-minute hold times; Gas tightness testing conducted after strength test approval, using compressed air or inert gas with leak detection solution on all welded joints and connections; Outlet pressure setting error verification at minimum inlet pressure with 10% of rated flow; Safety device activation pressure testing by gradually increasing pressure until device activates, repeated three times; Rated flow testing converting measured flow to standard conditions using temperature, pressure, and compressibility corrections; Shut-off pressure testing at maximum inlet pressure by slowly closing downstream valves; and Insulation resistance measurement using insulation resistance testers. Factory inspection requires 100% testing of critical items including NDT, strength, gas tightness, and insulation performance, while type inspection covers all specified parameters annually or upon significant design changes.
FAQs
What products are regulated under GB 27791-2020?
GB 27791-2020 applies to city gas pressure regulating installations with a maximum inlet working pressure of 10.0 MPa and operating temperatures between -20°C and 60°C. It does not apply to underground installations.
What are the main updates from GB 27791-2011 to GB 27791-2020?
The 2020 version introduces several key changes, including modified scope and terminology, updated model numbering rules, added NDT technical grades, revised gas tightness test pressures, modified safety device activation pressure setting errors, and updated insulation performance requirements. It also adds provisions for handling NDT failures.
How does GB 27791-2020 differ from international standards?
GB 27791-2020 references numerous Chinese national standards for materials, valves, and pressure equipment. While some referenced standards align with international practices (e.g., ISO equivalents for certain pipe and flange specifications), the standard is specifically tailored to Chinese regulatory requirements under TSG regulations. Manufacturers must comply with GB 27791-2020 directly for Chinese market access.
The summary above provides a high-level overview of GB 27791-2020. To ensure complete compliance for your gas pressure regulating installations entering the Chinese market, a precise and professional translation of the full technical specifications is essential. Purchase our high-quality English translation of GB 27791-2020 today to access all detailed parameters, material specifications, testing procedures, and inspection criteria.
Applicability hints
- Type
- Product
- CCS
- P47
- ICS
- 91.140
- Competent department
- Ministry of Housing and Urban-Rural Development
- Technical committee
- Ministry of Housing and Urban-Rural Development
Relationships
Replaces:GB 27791-2011