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Eastern Steel Manufacturing Co.,Ltd is a leading manufacturer and distributor of seamless steel pipe, welded steel pipe, OCTG products and fittings. We supply first-step processing, semi-finished parts and finished parts to help our clients meet fabrication requirements beyond their capacity or to improve operations by moving forward the pre-production processing.
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As key connectors in pipeline systems, the precise matching of materials and specifications of threaded pup joints directly determines the safety and economy of the system. This article deeply analyzes the specification characteristics of carbon steel, stainless steel and alloy steel threaded pup joints from the three dimensions of material science, process standards and engineering applications.
Carbon steel threaded pup joints
The materials are generally Q235, 20# steel, etc. Its specifications are mainly divided according to nominal diameter (DN) and length. The nominal diameter range is wide, and DN6-DN100 are very common. For example, the DN15 carbon steel threaded pup joint, the outer diameter is usually around 21.3m, and its length specifications have a variety of options such as 50mm, 100mm, and 150mm. It is mainly used in general industrial pipeline systems and low-pressure civil pipeline systems. It is often used in conjunction with seamless steel pipe or mild steel tube. Some are used in hydraulic tubes systems to connect some small valves or instruments and other equipment.
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Specification system (ASTM A106/GB/T14976) |
||||
|
Nominal diameter (DN) |
Actual outer diameter (mm) |
Wall thickness range (mm) |
Standard length (mm) |
Thread standard |
|
6 |
10.2 |
1.5-2.0 |
30-50 |
BSPP |
|
15 |
21.3 |
2.0-2.8 |
50-150 |
NPT |
|
50 |
60.3 |
3.0-4.5 |
200-300 |
UN/UNF |
Stainless steel threaded pup joint
Common materials include 304 and 316 stainless steel. 304 stainless steel threaded pup joint is widely used in food, pharmaceutical and other industries due to its good corrosion resistance. There are also many options for its nominal diameter, such as DN8- DN80. Taking the DN25 304 stainless steel threaded pup joint as an example, the outer diameter is about 33.7mm, and the length can be 80mm, 120mm, etc. 316 stainless steel threaded pup joint is more suitable for use in highly corrosive environments, such as marine engineering, chemical industry, etc. Its specifications and dimensions are similar to those of 304 stainless steel, but the price is relatively high.
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Parameters |
304 (06Cr19Ni10) |
316L (022Cr17Ni12Mo2) |
|
Nickel content |
8-10.5% |
10-14% |
|
Molybdenum content |
- |
2.0-3.0% |
|
Pitting resistance equivalent PREN |
19.5 |
27.8 |
|
Applicable chloride ion concentration |
≤200ppm |
≤2000ppm |
Alloy steel threaded pup joint
For example, alloy steel materials such as 15CrMo and 12Cr1Mov are mainly used in high-temperature and high-pressure pipeline systems. The nominal diameter is generally from DN10-DN65, and its dimensional accuracy requirements are relatively high. For example, the 15CrMo alloy steel threaded pup joint DN20 has an outer diameter of about 26.9mm and a length of 70mm-150mm depending on the specific usage scenario. It has important applications in high-temperature and high-pressure pipeline connections such as thermal power generation and petrochemicals. It can be used with drill pipes and casings and is an important component in the oil and gas, energy, and refining industries.
|
Nominal diameter (DN) |
Pressure rating (MPa) |
Minimum wall thickness (mm) |
Thread sealing form |
|
10 |
25 |
3.2 |
Rc/Rp taper pipe thread |
|
32 |
16 |
5.6 |
API round thread |
|
65 |
10 |
8.8 |
BUTTRESS special tooth shape |
Selection and installation suggestions
1. Material priority
According to the corrosiveness of the medium, temperature, and pressure, select carbon steel → 304 → 316L → alloy steel in descending order.
2. Size matching
Strictly select according to the nominal diameter (DN), wall thickness, standard length and thread standard of the pipeline to avoid secondary processing on site.
3. Reliable sealing
The combination of tapered pipe thread (Rc/Rp) with conical gasket and polytetrafluoroethylene gasket can improve the sealing performance.
4. Inspection and maintenance
The burrs and chamfers should be strictly removed before assembly; during operation, the threaded connection parts should be regularly checked for looseness and leakage.
Read more: What Is The Minimum Length of Welded Pipe Pup Joints?
E-mail: sales@eastern-steels.com
