What Does the CC Prefix Mean in ASTM A671 Pipe Grades?

The Direct Answer: CC Refers to a Specific Plate Family

In ASTM A671/A671M, the CC prefix identifies a family of electric-fusion-welded pipe grades made from plain carbon, killed, fine-grain pressure-vessel-quality steel plate specified by ASTM A516/A516M. The suffix number identifies the corresponding ASTM A516 plate grade: CC60 uses Grade 60 plate, CC65 uses Grade 65 plate, and CC70 uses Grade 70 plate.

The complete ASTM A671 designation also needs a separate pipe Class, such as CC65 Class 22. CC65 is the material grade; Class 22 is not another steel grade. This distinction is essential for specifying heat treatment, examination and other manufacturing requirements. The applicable edition of ASTM A671/A671M governs the exact requirements.

CC60, CC65 and CC70: What Changes?

A useful way to read the designation is to start with the underlying plate certificate. For CC60, CC65 or CC70, confirm that the stated ASTM A516/A516M grade corresponds to the CC suffix. Then review the actual reported chemical composition and mechanical properties rather than assuming that every heat has identical values. The plate standard provides requirements for the selected grade, while production results show how a particular heat performed. This distinction matters for welding procedure selection, material traceability and procurement review. The numeric suffix should never be interpreted as a guaranteed pressure capacity or a substitute for the design-code allowable stress.

CC60 corresponds to ASTM A516/A516M Grade 60; CC65 corresponds to Grade 65; and CC70 corresponds to Grade 70. The numeric suffix is associated with the corresponding plate strength grade and is not a pipe pressure rating, an operating temperature or a pipe Class.

Actual chemical composition and mechanical-property acceptance criteria must be checked against ASTM A516/A516M and any applicable general requirements. ASTM A20/A20M sets general requirements for pressure-vessel plate; it does not replace the specific A516 grade requirements. ASTM A370 provides mechanical testing methods and definitions; it does not independently assign CC60, CC65 and CC70 strength values.

Increasing the grade number does not automatically establish higher allowable stress for every design temperature or guarantee better weldability or toughness. Engineers should use the material properties and allowable-stress provisions of the applicable design code.

How Grade Differs from Class in ASTM A671

For a purchase order, writing only “ASTM A671 CC65” leaves important information unresolved. The purchaser also needs to identify the applicable Class and the standard edition, because the manufacturing and inspection requirements cannot be reconstructed from the material grade alone. Conversely, a Class designation does not establish which plate grade was used. A complete designation therefore combines two different sets of information: material identity and pipe production requirements. Dimensions, supplementary examinations, certification type and service conditions remain separate order details. Checking each field independently helps prevent disputes during inspection and avoids substituting a visually similar but technically different product.

Grade identifies the plate-material family. Class identifies specified pipe manufacturing and examination conditions, including applicable heat-treatment and radiographic and pressure-test provisions. For example, “ASTM A671 CC65 Class 22” communicates more than “CC65” alone.

The exact obligations for any Class must be read from the selected ASTM A671 edition. Do not describe all Classes as requiring identical heat treatment, full-length UT and RT, or universal hydrostatic testing. Additional project inspection may be specified, but it should be distinguished from baseline standard requirements.

The Grade/Class designation also does not define pipe dimensions, allowable design pressure or suitability for a particular process fluid. Those are determined through the design specification, material qualification and order details.

Why the Base Plate Specification Matters

The connection between plate properties and finished-pipe performance is important because forming and welding introduce additional variables. Plate strength and chemistry influence weldability, but the finished seam must also satisfy the applicable weld procedure and examination requirements. A purchaser may need to review consumable selection, preheat, heat input and any specified post-weld heat treatment. For low-temperature duties, impact-test conditions should be matched to the project’s design basis and material requirements. The plate certificate is necessary evidence, but it is not a substitute for the finished-pipe inspection and test records required by the order.

EFW pipe is formed and welded from steel plate, so the plate specification and grade affect chemistry, strength, toughness and welding behavior. The purchaser should confirm the plate grade and heat number on the material test certificate and verify traceability from plate to finished pipe.

Welding procedure qualification, heat input, consumables, preheat and any required heat treatment must be appropriate to the material and thickness. The finished weld and heat-affected zone can have different properties from the parent plate. Weld examination and mechanical tests are therefore important parts of the applicable acceptance process.

For low-temperature service, the design minimum metal temperature, required impact toughness, product grade and governing code must be considered together. The fact that ASTM A671 covers atmospheric and lower temperatures does not make every CC-grade pipe suitable for cryogenic LNG service near −162°C. Such temperatures require a separately appropriate material system and qualification.

Comparison with Related Specifications

Selection should follow the intended service rather than the superficial similarity of product names. ASTM A671 is commonly considered for atmospheric and lower-temperature service, whereas ASTM A672 and ASTM A691 address other temperature, pressure and material combinations. ASTM A333 uses a different product and grade framework for low-temperature piping. API 5L is directed at line pipe and should be assessed against pipeline requirements rather than treated as an automatic equivalent to a pressure-piping specification. When reviewing a substitution request, the engineer should compare base material, manufacturing route, mechanical properties, examination requirements and design-code acceptance, not only nominal outside diameter and wall thickness.

ASTM A671/A671M covers EFW pipe for atmospheric and lower-temperature service. ASTM A672/A672M addresses EFW pipe for high-pressure service at moderate temperatures, and ASTM A691/A691M covers EFW carbon and alloy steel pipe for high-pressure service at high temperatures. ASTM A333/A333M addresses seamless and welded steel pipe for low-temperature service under a different product framework.

API 5L concerns line pipe for pipeline transportation systems and uses its own grade, delivery and inspection provisions. Material specifications should not be substituted merely because the nominal strengths or product dimensions appear similar.

Inspection and Purchasing Checklist

A practical receiving review should compare the purchase order, pipe markings and inspection documents. Check that the reported heat number links the finished pipe to the specified plate material, that the stated Grade and Class match the order, and that the required examinations have documented results. If impact testing or additional nondestructive examination was specified, verify the method, coverage, test temperature where applicable, and acceptance criteria. Any nonconformity should be resolved through the agreed project procedure before material release. This documentation-based approach is more reliable than accepting a generic statement that the pipe complies with ASTM A671.

A complete inquiry should identify the governing ASTM A671/A671M edition, grade, Class, outside diameter, wall thickness, length, required plate condition, service temperature, governing piping code and supplementary requirements. Where impact testing, hardness examination, extra NDT, coating or third-party inspection is needed, state the test methods and acceptance criteria explicitly.

Before shipment, verify plate heat certificates, chemical and mechanical test results, welding procedure records, specified heat-treatment records, examination reports and traceability. The inspection document type—such as EN 10204 3.1 or 3.2 where contractually required—should be specified in advance.

Pressure rating must be calculated under the applicable design code using material allowable stress, temperature, diameter, wall thickness, weld factors and corrosion allowance. Neither “CC70” nor “Class 22” is a stand-alone pressure rating.

Conclusion

The CC prefix in ASTM A671 identifies the ASTM A516 fine-grain, killed carbon-steel plate family. CC60, CC65 and CC70 correspond directly to A516 Grades 60, 65 and 70. The Class designation separately controls defined manufacturing and inspection conditions. Accurate ordering requires both identifiers, the governing edition and the project-specific design and testing requirements.

Frequently Asked Questions

What does CC mean in ASTM A671?

It denotes the pipe-grade family associated with ASTM A516/A516M fine-grain, killed carbon-steel pressure-vessel plate.

What is the difference between CC60 and CC65?

CC60 uses ASTM A516 Grade 60 plate, while CC65 uses ASTM A516 Grade 65 plate. Selection depends on the design and applicable material requirements.

What does Class 22 mean?

It is a pipe Class designation, not a material grade. Its specific heat-treatment and examination requirements must be verified in the applicable ASTM A671 edition.

Can CC70 be used at −162°C?

Do not assume so. LNG cryogenic duty requires an appropriate material system and verified design-code compliance; the CC70 designation alone does not establish suitability.

Does ASTM A671 provide a single pressure rating?

No. Pressure design depends on the applicable piping code, allowable stress, dimensions, temperature, weld factors and other design conditions.

About LONGMA

LONGMA is a Hebei-based manufacturer of round welded steel pipes, with more than 20 years of industry experience. Its manufacturing facility covers 230,000 m², and annual production exceeds 500,000 tonnes. For project inquiries, specify the required product standard, grade, dimensions, inspection scope and applicable service conditions. Contact: info@ilongma.com.