Threaded Pipe
- Standard: ASTM A53/A106
- Material: carbon steel, stainless steel
- Surface treatment: galvanized
- Temperature range: -29°C ~ 260°C
- Length: 4-6 meters, or as required
- Process: Cold-drawn, welded, seamless
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Threaded pipe is a connector that forms a specific thread structure at the end of the pipe through precision machining technology. The pipe is connected by the mechanical bite force between the internal and external threads. This pipe is usually made of galvanized steel, stainless steel or copper.
The thread design of the threaded pipe must strictly follow international standards. During installation, raw tape or sealant should be used to fill the gaps between the threads to enhance the sealing and ensure the compatibility and reliability of the connection.
The advantages of this pipe are easy installation, repeatable disassembly and maintenance, and the cost is lower than welding or flange connection. It is widely used in small and medium-caliber scenes such as fire water supply, industrial compressed air and building water supply and drainage, but it has strict requirements on thread processing accuracy and installation torque. Over-tightening can easily cause thread deformation and leakage.
Threaded Pipe Supply Range
Thread Pipe Specification
NPT thread: 1/8“~3/4”, taper 1:16 (ASME B1.20.1)
BSPT thread: G1/8~G3/4, taper 1:16 (ISO 7-1)
Material and Surface Finish
Galvanized steel: ASTM A53/A106, zinc layer ≥85 μm (salt spray ≥500h)
Stainless steel: 304/316L (Cr 18~20%, Ni 8~12%), Cl- corrosion resistant (≤200 ppm)
Copper tube: C12200 (Cu≥99.9%), oxide film thickness 2~5 μm
Sealing test parameters
Water pressure test: 1.25~1.5 times the working pressure, holding pressure for 5~10 minutes (no leakage)
Air tightness test: 0.5~0.6 MPa compressed air, leakage rate ≤ 0.1 bubble/minute (GB/T 13927)
Thread precision range
Tooth angle tolerance: ±0.5° (NPT/BSPT)
Pitch error: ≤±0.02 mm or ≤±0.04 mm per 25.4 mm length
Taper tolerance: ≤±0.05 mm over the whole length (1:16 taper)
Tolerance of center diameter: 6H/6g grade, allowable deviation ±0.01~0.03 mm
Threaded Type-NPT/ BSPT/ Rc/ R
NPT Threaded Pipe
Tooth angle/taper: 60° tooth angle, taper 1:16, depends on thread deformation to realize sealing.
Sealing method: need to wrap the raw material tape or apply sealant to fill the gap between the threads.
Application Scenario: North America oil and gas pipelines, industrial compressed air systems (pressure resistance ≤ 10 MPa).
Standard specification: ANSI/ASME B1.20.1, China corresponding standard GB/T 1271625.
BSPT Threaded Pipe
Tooth angle/taper: 55° tooth angle, taper 1:16, self-sealing by taper extrusion.
Sealing method: Theoretically, no auxiliary materials are required, in practice, raw material tape may be added to enhance sealing.
Applicable scenes: Europe and Commonwealth countries water supply, gas pipelines (DN15-DN50).
Alias and standards: the old domestic name ZG (such as Rc for the internal thread, R for the external thread), the standard GB / T 73061
Rc/R Threaded Pipe
Tooth angle/taper: 55° tooth angle, 1:16 taper, fully compatible with PT threads.
Sealing fit: Rc and R taper to taper connection, better sealing than flat threads.
Application: High pressure interface for chemical equipment.
| Thread Type | Tooth shape | Taper | Sealing method | Pressure |
| NPT | 60° | 1:16 | Raw Material Tape/Sealant | ≤40 MPa |
| PT/BSPT | 55° | 1:16 | Tapered self-sealing | ≤25 MPa |
| G | 55° | —— | End Gaskets/O-Rings | ≤1.6 MPa |
| M | 60° | —— | Non-sealed or auxiliary materials | Unpressurized scenario |
Threaded Pipe Advantages and Applicatio Scenario Analysis
Advantages
High Pressure Sealing
Precision thread engagement: This is the most critical link. It must pass NPT (National Pipe Thread) or BSPT (British Standard Pipe Thread), and the thread taper matching ratio is 1:16. This thread connection method can withstand a working pressure of 10-35MPa.
Multi-material adaptation: Supports a variety of materials to meet the sealing requirements of different media (water, oil, gas), such as galvanized steel, stainless steel, copper, etc.
Installation flexibility and maintenance convenience
Welding-free assembly: No complicated welding or heat treatment is required, only simple tools are needed to complete it, saving 80% of the installation time.
Detachable design: supports repeated disassembly and assembly, convenient for pipeline system maintenance or partial replacement.
Environmental adaptability
Resistant to extreme working conditions: Stainless steel threaded pipes can withstand extreme working conditions and work stably in extreme temperature ranges, from as low as -196°C to as high as 450°C. 316L stainless steel material has excellent corrosion resistance and can withstand corrosive environments with Cl- concentrations ≤500 ppm.
Anti-seismic and displacement compensation: Threaded connections allow for smaller angle deviations (≤3°), which are suitable for geologically unstable areas or thermal expansion and contraction scenarios
Economical
Low maintenance costs: threaded fittings can be replaced at 40-60% less cost than flanged or welded connections.
High material utilization: high-frequency welded pipe (e.g. SY/T 5037 standard) wall thickness error ≤±5%, reducing material waste.
Main application scenarios
Municipal and construction engineering
Water supply and drainage system: DN15-DN50 galvanized threaded pipes are used for water and sewage transmission, pressure resistance ≥ 6 MPa.
Gas pipeline: NPT threaded stainless steel pipe connecting natural gas branch line, leakage rate ≤ 0.1 bubbles/minute.
Industrial field
Petrochemical industry: The safety of high-pressure oil and gas transmission pipelines is extremely important, and threaded pipes that meet the API 5CT standard are usually used, with a bursting pressure of ≥35MPa.
Mechanical hydraulic system: BSPT threaded copper pipes are used as the core components of the hydraulic oil circuit, which are resistant to instantaneous pressure fluctuations.