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We offer custom services based on engineering needs. This includes special thread specifications, special-shaped shoulder structures, and coating treatment solutions. For example, the development of gradient expansion coefficient composite materials can adapt to the day and night temperature difference environment of more than 70℃.

Shouldered steel pipes are mainly made of the following three types of materials:

• Alloy structural steel‌: such as 4145H (yield strength 758MPa), is suitable for conventional high-pressure conditions.
• Corrosion-resistant alloy‌: including UNS S31803 duplex stainless steel (Cl⁻ tolerance＞200ppm).
• High-temperature alloy‌: Inconel 625 can maintain stable mechanical properties at 650℃.

Shouldered Pipe is certified by UL 1709 standard and maintains structural integrity for more than 5 minutes in a 1093℃ fire test. The leakage is controlled within 1L/min·m, meeting the fire resistance requirements of NFPA 13 for high-pressure fire protection pipes.

The nickel-based alloy version has an annual corrosion rate of <0.02mm in a 3.5% NaCl solution and is certified by NACE MR0175 standard. For hydrogen sulfide environments, the material hardness must be controlled below HB 23756. Ultra-low carbon stainless steel (such as 304L) performs well in weak acid media with pH>4.

The pipe specifications supplied by UNIASEN cover a wide range of industrial needs. The specific parameters are as follows:

Explanation‌:

• Small-diameter pipes (such as 50mm) are mostly used in high-pressure hydraulic systems, and large-diameter pipes (such as 600mm) are suitable for low-pressure transmission scenarios.
• Special sizes can be customized, and the pipe end connection form (such as flat head, thread or flange) and medium temperature parameters must be provided.

The following key factors should be considered comprehensively in the selection:

‌Medium characteristics‌:

• Corrosive media (such as acid and salt spray) need to choose duplex stainless steel or nickel-based alloy materials.
• For fluids containing solid particles, it is recommended to increase the wall thickness or use wear-resistant coatings (such as tungsten carbide).

Pressure and temperature‌:

• Calculate the minimum wall thickness according to the working pressure (formula: wall thickness = pressure × diameter / (2 × material strength × safety factor)).
• High-temperature alloys (such as Inconel series) should be used when the temperature is ＞150℃.

‌Environmental conditions‌:

• The low-temperature impact toughness of the material (Charpy impact energy ≥80J) needs to be verified in extremely cold areas (such as -50℃).
• The marine environment needs to be equipped with hot-dip galvanizing or PTFE coating to extend the service life.

• Conventional working conditions‌: Design life ≥20 years (based on ASME B31.3 standard fatigue calculation).
• Extreme Environment‌: Deep-sea pipelines have passed 200,000 pressure cycle tests (DNV-OS-F101 standard). In corrosive media environments, the service life can be extended to 15 years by increasing the wall thickness by 10%-15%.
• Warranty Commitment‌: Provide a 10-year limited warranty (including annual non-destructive testing service).