Determining BOQ attribution of gas pipelines: the boundary between GB/T 50856-2024 Appendix H (industrial piping) and Appendix K (water supply/drainage, heating, gas), and the division with municipal GB/T 50857-2024

Topic Positioning

This card resolves the attribution of gas pipelines (and various plant piping) when compiling BOQs: list under GB/T 50856-2024 Appendix H "industrial piping works" or Appendix K "water supply/drainage, heating, gas works", and the boundary between plant piping and the network works of GB/T 50857-2024 municipal measurement.

Core Conclusions

1. Correct the framing first: "industrial piping" and "water supply/drainage, heating, gas" are not two standards but two appendices of the one GB/T 50856-2024 (H / K); there is no "industrial BOQ vs installation BOQ" choice — the question is which appendix.

2. Two yardsticks: (1) position (municipal boundary first); (2) use (production vs domestic).

3. Municipal boundary (GB/T 50857-2024 Clause 3.0.4, verbatim): "The boundary between the network works of this standard and the industrial piping works of GB/T 50856: water pipes at the plant-entrance meter pit; drainage at the first storm/sanitary manhole outside the plant wall; heat and gas at the first meter (valve) at the plant entrance"; "the boundary with the water supply/drainage, heating, gas works of GB/T 50856: outdoor water/drainage/heating/gas pipes at the connection manhole with municipal pipes." Beyond the boundary (municipal side), list per GB/T 50857-2024 Appendix E network works (pipe laying 040501).

4. Use test (GB/T 50856-2024 Appendix H, verbatim):

• H.15.1: "Industrial piping works" applies to the conveyance of production media within plant areas — between workshops, plants, stations, and tank farms — and to pipes within the first plant connection point conveying water, drainage, steam, and gas shared by production and domestic use.
• H.15.3: domestic water, drainage, steam, and gas piping within plant areas shall be listed per Appendix K.

5. Synthesis: production or shared -> Appendix H by pressure class (030801 low / 030802 medium / 030803 high; classes: low 0 < P <= 1.6 MPa, medium 1.6 < P <= 10 MPa, high 10 < P <= 42 MPa; steam P >= 9 MPa or working temperature >= 500 C); domestic (in-plant domestic, indoor/outdoor civil buildings) -> Appendix K Table K.1.1 (code 031001).

6. Cases always listed under Appendix H:

• GB/T 50857-2024 E.5.2: high-pressure pipes, stainless pipes and their fittings and valves, and weld NDT shall be listed per GB/T 50856 Appendix H;
• GB/T 50856-2024 Appendix K, K.9.6, Item 10: directly buried pre-insulated pipes shall be listed per Appendix H.

7. Differences between the appendices (affecting assembly):

• Appendix H: fittings, flanges, and valves are separate BOQ items; fittings (elbows, tees, crosses, reducers, couplings, caps, square-expansion-bend elbows, primary instrument elements on pipe) by "count"; tees/crosses/reducers by the larger bore; branch taps by pipe diameter below half the main are not counted; flange-connected fittings count as flange items only; pressure testing, blowing, flushing of fittings are in the low/medium pipe work content.
• Appendix K: pipe quantities do not deduct valves, pressure reducers, traps, meters, expansion joints and other fittings or chambers; square expansion bends enter the pipe length; all pipe items include pressure testing and blowing/flushing; drainage includes riser cleanouts and vent caps; gas purging is included (GB/T 50857-2024 E.5.4).
• Indoor/outdoor boundaries (Appendix K K.9.1): water/heating at 1.5 m outside the building face (at entrance valves where provided; heating at the circulation-tee of entrance assemblies set outdoors); drainage at the first inspection manhole; gas: underground entries at the first indoor valve, above-ground entries at the first tee outside the wall.

Applicable Boundaries

• Based on the 2024 GB/T 50856-2024 and GB/T 50857-2024; for BOQ code attribution only — not a substitute for design, construction, or acceptance codes.
• Three scenarios, three paths, do not mix: town municipal gas (beyond the meter/connection manhole) -> GB/T 50857 Appendix E; in-plant production/shared -> GB/T 50856 Appendix H; in-plant domestic and civil buildings -> GB/T 50856 Appendix K.
• "High-pressure, stainless pipes and their fittings/valves, weld NDT, directly buried pre-insulated pipes under Appendix H" is mandatory regardless of project nature or position.
• For assembly, cross-check the local quota volume's chapter attribution.

Further Reading

• GB/T 50856-2024 Appendix H: H.15.1 (scope), H.15.2 (pressure classes), H.15.3 (domestic to Appendix K), Table H.1.1 low-pressure (030801), H.2.1 medium (030802), high (030803), H.4.1 low fittings (030804), H.5.1 medium fittings (030805), H.15.7 (fitting notes).
• GB/T 50856-2024 Appendix K: Table K.1.1 (031001), K.9.1 (boundaries), K.9.6 (notes).
• GB/T 50857-2024: Clause 3.0.4 (boundaries), Appendix E networks (040501, E.5.2, E.5.4).