Selecting Steel Pipes for High-Temperature & Low-Temperature Service: ASTM A671 vs. ASTM A672

Introduction

Extreme temperature industrial pipelines used in oil and gas, power generation, low temperature storage and municipal infrastructure rely on durable welded steel pipe to resist hot cracking and pressure-induced deformation. All heavy-duty pipeline projects require strict compliance with standardized carbon steel pipe specifications, because sub-zero brittleness and high-temperature creep are two common causes of failure under extreme working conditions. It is very important for project engineers and purchasing teams to distinguish between ASTM A671 and ASTM A672 EFW pipeline standards, because both standards are widely manufactured and supplied by qualified carbon steel pipeline manufacturers around the world.

These two EFW pipe standards both adopt plate-formed submerged arc welding to produce premium Tube d'acier LSAW, yet they are engineered for completely different temperature scenarios. ASTM A671 focuses on low-temperature impact toughness, while ASTM A672 aims at high pressure and medium and high temperature stability. This article clarifies their differences in material grades, heat treatment, testing protocols and application scenarios and guides users to select compliant pipe specifications and reliable pipe manufacturers for extreme-temperature pipeline projects.

1. Understanding ASTM A671: EFW Steel Pipe for Low-Temperature Service

1.1 Scope & Design Purpose

ASTM A671 covers electric-fusion-welded steel pipe intended for atmospheric and lower-temperature service where notch toughness is required. The core design gives priority to the low-temperature notch toughness to avoid brittle fracture in the sub-zero environment. This standard is applicable to large-diameter pipelines of NPS 16 and above, with a minimum wall thickness of 6 mm, and is widely used in low-temperature industrial systems.

As a mainstream product of professional carbon steel pipe manufacturers’ facilities, ASTM A671 EFW steel pipe is commonly manufactured using plate-forming and submerged arc welding processes, including JCOE and other longitudinal welding methods. Its strict chemical impurity control can effectively prevent microcrack propagation under low-temperature thermal shock, which is in line with international cold service pipe specifications.

1.2 Common Grades & Heat Treatment Classes

The ASTM A671 grades correspond to specific pressure vessel steel plates and conform to the unified industrial pipeline specifications.

• CA55 / CB60: Made from ASTM A442 steel plates (historical specification referenced in the standard)
• CC60 / CC65 / CC70: Adopts fine-grain A516 Gr 60/65/70 plates, ideal for cryogenic pipeline systems
• CD70 / CD80: Uses quenched-and-tempered A537 steel for ultra-low-temperature arctic pipelines

Class codes (12, 22, 32) define heat treatment and radiographic inspection requirements (Data Source: ASTM International specifications):

1. First digit: Heat treatment standard (1=as-welded, 2=stress-relieved, 3=normalized)
2. Second digit: Weld radiographic inspection coverage (2=100% full-length RT detection)

Class 22 is the most widely used grade, featuring stress relief treatment and full weld inspection to eliminate residual stress and prevent low-temperature cracking.

1.3 Main Applications

ASTM A671 Tube d'acier LSAW is primarily used in low-temperature and cryogenic applications:

• Liquefied natural gas, liquefied petroleum gas and liquid nitrogen low-temperature pipelines.
• Arctic oil and gas collection and main pipelines.
• Municipal water supply and industrial process pipelines in cold regions.
• Sub-zero mining and energy fluid transmission systems.

2. Understanding ASTM A672: EFW Steel Pipe for High-Pressure and Moderate-to-High Temperature Service

2.1 Scope and Design Purpose

ASTM A672 covers electric-fusion-welded steel pipe intended for high-pressure service at moderate temperatures. Different from the low temperature toughness design of A671, this standard optimizes the microstructure and chemical composition of steel to maintain stable tensile strength and creep resistance under long-term high temperature thermal stress.

A professional carbon steel pipe factory has established an independent production process for A672 welded steel pipe to meet high-temperature service standards. It has the same size range as A671 and can provide flexible size matching for high-temperature industrial projects. Large-diameter, heavy-wall ASTM A672 pipes are commonly manufactured as customized LSAW products for demanding industrial applications.

2.2 Common Grades & Material Features

A672 grade focuses on high-temperature structural stability, with mainstream plate materials as follows:

• A45 / A50: Low-carbon A 285 C plates for low-pressure medium-temperature pipelines
• B60 / B65: A515 Gr 60/65 plates for steam and medium-pressure thermal piping
• C60 / C70: A516 Gr 60/70 plates for high-pressure boiler and chemical process pipelines

Although partial A671 and A672 grades adopt the same base plates, their industry pipe specifications differ greatly in testing standards. Unlike ASTM A671, ASTM A672 generally does not require mandatory low-temperature impact testing unless specified in project requirements.

2.3 Main Applications

ASTM A672 welded steel pipe serves high-pressure and high-temperature industrial fields:

• Power plant boiler steam headers and superheater connecting pipelines.
• Refinery and chemical plant high-temperature process fluid piping.
• Geothermal energy circulation and district heating trunk pipelines.
• High-pressure industrial compressed gas transport systems.

3. Key Differences: ASTM A671 vs. ASTM A672

The table below summarizes core differences compliant with official ASTM standards and industrial pipe specifications:

4. Manufacturing Processes of EFW & LSAW Steel Pipe

4.1 Standard Production Workflow

Certified carbon steel pipe manufacturer mills like Allland produce A671 and A672 welded steel pipe via standardized JCOE forming and submerged arc welding processes, fully complying with industry pipe specifications:

1. Raw plate inspection and dimension verification.
2. Precision cutting, blanking and edge milling.
3. Plate pre-bending and JCOE cylindrical forming.
4. Longitudinal seam pre-welding, internal and external submerged arc welding.
5. Straightening, chamfering and customized heat treatment.
6. Ultrasonic flaw detection, hydrostatic test and radiographic inspection.
7. Degaussing, marking and anti-corrosion coating (3 LPE/FBE can be selected).

4.2 EFW Pipe vs. Conventional LSAW Pipe

EFW pipe and conventional Tube d'acier LSAW share the same high-precision forming and welding technology, ensuring uniform weld quality and mechanical performance. The core difference is the customized test rules defined by different industry pipeline specifications. A671 requires strict low-temperature impact testing, and both standards enforce specific post-weld heat treatments (PWHT), while ordinary LSAW products may only undergo ambient-temperature routine inspections.

4.3 Core Quality Control Standards

Qualified welded steel pipe for extreme temperature must pass strict nondestructive testing, weld quality inspection and mechanical performance verification. Professional carbon steel pipeline manufacturers strictly execute ASTM-mandated heat treatments and mechanical testing to avoid pipeline failure under extreme temperature and pressure.

5. How to Select a Qualified Carbon Steel Pipe Manufacturer

5.1 Supplier Qualification Checklist

Sourcing compliant A671/A672 welded steel pipe requires suppliers to meet core technical standards matching official industry pipe specifications:

• Complete raw material traceability and official mill test certificates.
• Advanced JCOE LSAW steel pipe production lines and professional heat treatment equipment.
• Independent NDT laboratories for RT, UT and impact testing
• Valid API 5L, ISO and ASTM international certifications
• Custom anti-corrosion coating and personalized pipe processing services.

5.2 Allland’s Professional Pipe Solutions

As a professional carbon steel pipe manufacturer located in Cangzhou (China’s pipe manufacturing base), Allland owns 2 JCOE LSAW steel pipe production lines and 5 anti-corrosion workshops, with an annual output of 200,000 tons of standard welded products. All products strictly comply with ASTM industry specifications, supporting customized production of A671 low-temperature and A672 high-temperature pipes.

Allland provides complete batch testing reports, MTC documents and compliance certificates, serving global clients including CNPC, CNOOC, ADNOC and Petrobras. It delivers stable, standard-compliant pipeline products for cryogenic, power generation and petrochemical projects worldwide.

6. Frequently Asked Questions (FAQ)

Q 1: Can an A672 pipe replace an A671 for low-temperature cryogenic service?

A: A672 welded steel pipe has no mandatory low-temperature impact testing requirement, and its material composition is not designed to resist brittle fracture at sub-zero temperatures. Per standard industry pipe specifications, only A671 Class 22/32 LSAW steel pipe is compliant for cryogenic pipeline projects.

Q 2: What do Class 12, 22 and 32 mean for A671/A672 pipes?

A: Class codes represent heat treatment and inspection standards (Data Source: ASTM International specifications). The first number refers to heat treatment types, while the second number defines the coverage of radiographic inspection of welds. Class 22 is the most versatile industrial grade with stress relief treatment and full weld inspection for extreme-temperature pipelines.

Q 3: How does the grade of the steel plate correspond to the final grade of the EFW steel tube?

A: All pipeline grades are derived from specific ASTM pressure vessel plate specifications, which are a core part of unified industry pipeline specifications. A671 CC60/CC70 matches A516 Gr 60/70 low-temperature plates, while A672 C60/C70 and B60 are manufactured from A516 and A515 pressure vessel plates respectively to adapt to different service environments.

7. Conclusion

The core difference between ASTM A671 and A672 lies in their target working temperatures and customized industrial specifications. ASTM A671 welded steel pipe is designed for low temperature and low temperature embrittlement resistance, while A672 is suitable for high pressure and medium-high temperature industrial systems. Both standards employ mature submerged arc welding technology but require different heat-treatment and testing procedures according to their intended service conditions.

Choosing a professional and certified carbon steel pipe manufacturer ensures full compliance with ASTM standards, avoiding pipeline safety risks caused by non-standard production and testing. For extreme-temperature pipeline projects worldwide, matching the correct pipeline standard and a reliable supplier is the key to long-term stable operation of infrastructure systems.