ASTM A691 2-1/4Cr EFW Alloy Steel Pipe

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Xi'an Dongmeng Group Co., Ltd. supplies ASTM A691 2-1/4Cr EFW Alloy Steel Pipe for large-diameter, high-pressure and elevated-temperature piping systems used in refineries, petrochemical plants, power generation and industrial process facilities. Manufactured from pressure-vessel-quality ASTM A387 Grade 22 2.25Cr-1Mo alloy steel plate by electric fusion welding with filler metal, A691 2-1/4Cr pipe is available in project-specific diameters, wall thicknesses, heat-treatment classes and inspection levels. Dongmeng Group supports Class 22, Class 42, Class 52 and other specified conditions, together with RT/UT, PMI, pressure testing, beveling, fixed-length cutting, MTC documentation and third-party inspection according to project requirements.

ASTM states that A691 pipe is produced from pressure-vessel-quality plate using electric-fusion welding with filler metal and is intended for high-pressure service at elevated temperatures. The nominal dimensional scope is 16 in. [400 mm] OD and larger with wall thicknesses up to 3 in. [75 mm].

The designation 2-1/4Cr identifies the chromium-molybdenum alloy family used for the pipe.

For ASTM A691 2-1/4Cr pipe, the plate material is based on ASTM A387 Grade 22, which ASTM identifies as having nominal alloy contents of:

Chromium: 2.25%

Molybdenum: 1.00%

Chromium contributes to elevated-temperature oxidation resistance and hardenability, while molybdenum contributes to elevated-temperature strength and creep performance.

This chemistry is closely related to the material system used for ASTM A335 P22 seamless pipe, but the two specifications should not be treated as interchangeable because their manufacturing route, dimensional scope and specification requirements are different.

The underlying ASTM A387 Grade 22 material typically falls within the following chemistry range.

*Exact chemistry limits must follow the applicable edition of ASTM A387/A387M, the specified plate class and the purchase order.

Published Grade 22 data confirms the characteristic 2.00–2.50% Cr and 0.90–1.10% Mo chemistry range.

For high-temperature pressure piping, purchasing only by the label "2-1/4Cr pipe" is not sufficient.

A project specification should control:

heat number;

plate specification;

plate grade and class;

Cr and Mo content;

weld metal chemistry;

heat treatment condition;

hardness;

mechanical properties;

applicable NDE;

final pressure testing.

This information should be traceable through the material certificate and pipe marking.

Mechanical requirements depend on the plate class, final heat treatment and ordered pipe class.

As a useful reference, ASTM A387 Grade 22 Class 2 plate commonly has the following room-temperature tensile requirements:

These values should not automatically be used as guaranteed finished-pipe properties without confirming the ordered A691 grade, plate class, pipe class and applicable project specification.

For procurement, the required tensile properties should therefore be written directly into the RFQ or technical data sheet.

One of the most important differences between ASTM A691 and many ordinary pipe specifications is its Class system.

Under ASTM A691, the grade tells you the material family, while the Class identifies the manufacturing heat treatment and whether radiographic examination and pressure testing are required.

Typical examples include:

The ASTM A691 class structure differentiates products by heat treatment, radiographic examination and pressure testing.

Do Not Send an RFQ for Only "A691 2-1/4Cr"

A technically complete inquiry should state, for example:

ASTM A691 Gr. 2-1/4Cr Class 22 EFW Pipe

rather than only:

A691 2-1/4Cr Pipe

because the latter does not fully define the required heat-treatment and inspection condition.

ASTM A691 pipe differs fundamentally from seamless chrome-moly pipe because it is produced from pressure-vessel-quality plate.

A typical production route includes:

1. Plate Identification

ASTM A387 Grade 22 plate is checked against the required heat number, chemistry, plate condition and certificate.

2. Plate Preparation

Plate edges are prepared for the required welding procedure and pipe geometry.

3. Forming

The plate is formed into cylindrical pipe shape using suitable forming equipment.

4. Electric Fusion Welding

The longitudinal seam is welded using an electric fusion welding process with added filler metal.

ASTM requires the weld metal to fuse smoothly and uniformly with the plate material.

5. Weld Inspection

The longitudinal weld is inspected according to the ordered A691 Class and project requirements.

6. Heat Treatment

Stress relieving, normalizing, normalizing and tempering, or quenching and tempering may be applied depending on the selected Class.

7. Mechanical Testing

Required tension, bend and related tests are performed in accordance with the specification and purchase requirements.

8. Nondestructive Examination

RT, UT or other NDE may be performed according to the ordered class, supplementary requirements and project specification.

9. Pressure Testing

Pressure testing is performed where required by the specified A691 Class.

10. Final Inspection & Traceability

Dimensions, surface, bevels, marking, heat number and documentation are checked before shipment.

Heat treatment is particularly important for 2.25Cr-1Mo alloy steel because welding produces a heat-affected zone whose hardness and microstructure must be controlled.

Depending on A691 Class, the finished pipe may be supplied:

without final pipe heat treatment;

stress relieved;

normalized;

normalized and tempered;

quenched and tempered.

For 2-1/4Cr material, published A691 reference data lists stress-relief/PWHT temperatures broadly in the 650–760°C range, although the exact procedure must be based on the specification edition, material condition, wall thickness, welding procedure and governing construction code.

For critical projects, buyers should specify:

PWHT temperature + holding time + heating/cooling rate + hardness acceptance + WPS/PQR requirements.

For refinery, pressure equipment and power projects, inspection should extend beyond dimensional checking.

Available project inspection requirements may include:

chemical composition verification;

material identification and heat-number traceability;

PMI;

tensile testing;

bend testing;

hardness testing;

weld visual examination;

radiographic testing;

ultrasonic examination;

hydrostatic or other specified pressure testing;

dimensional inspection;

wall-thickness measurement;

weld profile inspection;

end bevel inspection;

third-party inspection;

final MTC review.

ASTM A691 specifically addresses tension, bend and pressure testing together with requirements related to weld quality and repair.

ASTM A691 2-1/4Cr EFW pipe is particularly suited to large-diameter elevated-temperature pressure systems.

Typical applications include:

Oil Refining

high-temperature process lines;

refinery transfer piping;

hydroprocessing units;

reactor-related piping;

large-diameter chrome-moly headers.

Petrochemical Plants

process gas lines;

high-temperature hydrocarbon service;

hydrogen-containing process systems where permitted by the engineering design;

large-diameter pressure piping.

Power Generation

elevated-temperature steam systems;

boiler-related piping;

high-temperature headers;

auxiliary high-pressure systems.

Pressure Equipment

large process headers;

pressure-vessel connection piping;

heat-treatment furnace piping;

high-temperature process equipment connections.

Important: Material suitability must be determined from the applicable design code, design temperature, pressure, process medium, corrosion allowance, hydrogen conditions and required design life. The grade name alone should never be used to establish a safe operating limit.

These two specifications belong to the same broad 2.25Cr-1Mo alloy family, but they serve different manufacturing and dimensional needs.

Specify ASTM A691 2-1/4Cr when the project design allows EFW construction and large-diameter welded pipe is required.

Specify ASTM A335 P22 where the design specification explicitly requires seamless high-temperature alloy steel pipe.

They should not be substituted for each other solely because their nominal chromium and molybdenum contents are similar.

For fast and accurate quotation, provide the following information:

Standard: ASTM A691 / ASME SA691
Grade: 2-1/4Cr
Class: e.g. Class 22 / Class 42 / Class 52
Outside Diameter: ___ mm / inch
Wall Thickness: ___ mm / Schedule
Length: ___
Quantity: ___ pcs / tons
Heat Treatment: ___
RT Requirement: ___
UT Requirement: ___
Pressure Test: ___
Impact Test: if required
Hardness Requirement: ___
PMI: required / not required
PWHT Requirement: ___
Ends: PE / BE / special machining
MTC: EN 10204 3.1 / project requirement
Third-Party Inspection: SGS / BV / TÜV / customer-nominated agency if required
Design Code: ASME / project specification
Application: refinery / petrochemical / power / other

Providing these details at RFQ stage significantly reduces technical clarification cycles.

Dongmeng Group focuses on B2B industrial steel supply for project and engineering applications.

For ASTM A691 chrome-moly pipe orders, procurement support can include:

Material Traceability

Heat-number-controlled material identification and documentation help maintain traceability from plate material through the finished pipe.

Project-Based Dimensions

Large-diameter and heavy-wall requirements can be reviewed against ASTM A691 and individual project specifications.

Processing Support

Beveling, cutting, fixed-length preparation and other project-specific finishing can be coordinated according to the purchase specification.

Inspection Support

PMI, UT, RT, pressure testing, mechanical testing and third-party inspection can be arranged when required by the order.

Documentation

MTC and supporting inspection documentation can be prepared according to the agreed purchase requirements.

1. What is ASTM A691 2-1/4Cr pipe?

It is an electric-fusion-welded chromium-molybdenum alloy steel pipe manufactured from pressure-vessel-quality plate for high-pressure service at elevated temperatures.

2. What does 2-1/4Cr mean?

It identifies the 2.25Cr-1Mo alloy family. The corresponding ASTM A691 plate material is ASTM A387 Grade 22, which has nominal chromium and molybdenum contents of approximately 2.25% and 1.00%.

3. Is ASTM A691 2-1/4Cr the same as P22?

No. ASTM A691 2-1/4Cr is EFW welded pipe manufactured from plate, while ASTM A335 P22 is seamless alloy steel pipe. Their chemistry family is similar, but the specifications and manufacturing routes are different.

4. What plate is used to manufacture A691 2-1/4Cr pipe?

ASTM A691 identifies the 2-1/4Cr grade with ASTM A387/A387M Grade 22 plate.

5. What size does ASTM A691 cover?

The specification nominally covers pipe 16 in. [400 mm] OD and larger with wall thickness up to 3 in. [75 mm]. Other dimensions may be supplied if they comply with the other requirements of the specification.

6. What is ASTM A691 Class 22?

Class 22 identifies stress-relieved pipe with radiographic examination and pressure testing under the A691 class system.

7. Is radiographic testing mandatory for every A691 pipe?

Not automatically. Radiographic examination depends on the ordered A691 Class and any additional project requirements.

8. Does every A691 2-1/4Cr pipe require PWHT?

The required pipe heat treatment depends on the A691 Class, plate condition, welding procedure and applicable construction code. The purchase specification should define the required condition clearly.

9. Can PMI be performed?

Yes. PMI can be specified to verify alloy identity, particularly Cr and Mo, for projects requiring enhanced material verification.

10. Can the pipe be supplied with beveled ends?

Yes. Plain ends, standard bevels and project-specific machined ends can be specified in the purchase order.

11. What documents should I request with A691 pipe?

Typical project documentation includes MTC, heat-number traceability, chemistry and mechanical test results, heat-treatment records, NDE reports and pressure-test records where applicable.

12. What information is most important when requesting a quotation?

The most important information is grade + A691 Class + OD + wall thickness + length + quantity + heat treatment + NDE + pressure-test requirement + MTC requirement.

Looking for ASTM A691 2-1/4Cr Class 22, Class 42, Class 52 or another project-specific EFW chrome-moly pipe configuration?

Send us your:

Grade · Class · OD · Wall Thickness · Length · Quantity · Heat Treatment · NDE · Testing Requirements · Delivery Destination

Dongmeng Group can review the specification before quotation to help identify missing Class, testing or documentation requirements and reduce technical clarification during procurement.

Request a technical quotation with your pipe schedule, MTO or project specification.

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