Zhuojin Pipe Fitting Co., LtdWater and Heating Steel Pipes and Fittings in Building Applications
Literature Overview
The paper by Qiu Yurui and Du Qun, published in Pipe Technology and Equipment in 1999 (Issue 2, pp. 24-25), provides a comprehensive overview of steel pipes and fittings used in building water and heating systems. Authored by professionals from Nanjing Institute of Building Technology and Dalian Civil Building Design Institute, the article addresses standardization, applicable conditions, and basic usage methods for plumbing and HVAC piping systems. This work, though dated, remains relevant as a foundational reference for understanding the evolution of Chinese building piping standards.
Core Technical Content
The article systematically reviews the steel pipe grades and fitting types specified in Chinese national standards for building water supply and heating applications. The primary pipe types discussed include:
| Pipe Type | Typical Standard | Application | Pressure Rating |
|---|---|---|---|
| Hot-dipped galvanized seamless pipe | GB/T 8163 | Hot water heating systems | ≤1.6 MPa |
| Electric resistance welded pipe (ERW) | GB/T 3091 | Cold water supply | ≤1.0 MPa |
| Seamless carbon steel pipe | GB/T 8163 | High-temperature heating | ≤2.5 MPa |
| Galvanized welded fitting | GB/T 17241.6 | Threaded connections | PN10-PN16 |
The authors emphasize the distinction between threaded (screwed) connections and groove/pressed connections, noting that threaded fittings dominate residential applications while larger diameter systems in commercial buildings increasingly employ flanged or grooved couplings.
Standardization Framework
The paper highlights the hierarchical standardization system governing building piping in China:
- GB/T 8163 — Steel pipes for fluid transport (seamless)
- GB/T 3091 — Welded steel pipes for water supply
- GB/T 17241.6 — Threaded steel pipe fittings
- GB 50242 — Code for acceptance of building water supply and drainage works
- CJJ/T 28 — Technical code for building heating engineering
The authors note that standardization extends beyond material specifications to include dimensional tolerances, pressure test requirements, corrosion protection methods, and installation practices. They advocate for unified adoption of standard dimensions to reduce inventory complexity and improve interchangeability between manufacturers.
Engineering Practice Insights
From a practical standpoint, several key considerations emerge:
- Corrosion protection selection — Galvanizing is the default for cold water systems, but for hot water above 60°C, zinc coatings degrade rapidly. The paper recommends either bare steel with internal corrosion inhibitors or specialized coatings for sustained high-temperature service.
- Fitting selection methodology — The choice between elbows, tees, reducers, and caps must account for flow direction, pressure drop requirements, and future maintenance access. A 90° elbow is preferred over two 45° elbows in space-constrained installations, while the reverse applies where flow straightening is critical.
- Pressure testing — Hydrostatic testing at 1.5 times working pressure for 30 minutes without leakage is the minimum acceptance criterion, consistent with GB 50242 requirements.
Key Reflections
This literature serves as a valuable historical record of Chinese building piping practice at the turn of the millennium. The emphasis on standardization foreshadowed later developments including the widespread adoption of grooved mechanical joint systems (now governed by GB/T 3091 and related standards) and the shift toward stainless steel and copper alternatives in premium applications. For current engineers, the foundational knowledge of material selection and connection type determination remains directly applicable, even as specific standard numbers have been updated through subsequent revisions.