ASTM A334/A334M Standard Specification for Seamless and Welded Carbon and Alloy-Steel Tubes for Low-Temperature Service.

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ASTM A334 Gr.6 seamless steel tubes

ASTM A334 specification covers standard specification for several grades of minimum-wall-thickness, seamless and welded, carbon and alloy-steel tubes intended for use at low temperatures. The steel shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, copper, cobalt, and molybdenum. The number of tubes in a heat-treatment lot shall be determined from the size of the tubes. The tubes shall have a hardness number that does not exceed the prescribed Rockwell and Brinell hardness values. Several grades of steel shall conform to the following tensile properties: tensile strength, yield strength, and elongation. For Grades 1, 3, 6, 7, and 9, the notch-bar impact properties of each set of three impact specimens, including specimens for the welded joint in welded pipe, shall not be less than the prescribed values. Several mechanical tests shall be conducted, namely: flattening test; flare test (seamless tubes); flange test (welded tubes); reverse flattening test; hardness test; and impact tests. Hydrostatic or nondestructive electric test shall also be performed. Materials shall be tested for impact resistance at the prescribed temperature for the respective grades. Impact temperature reduction values shall be by any amount equal to the difference between the temperature reduction corresponding to the actual material thickness and the temperature reduction corresponding to Charpy specimen width actually tested.


1.1 This specification2 covers several grades of minimum-wall-thickness, seamless and welded, carbon and alloy-steel tubes intended for use at low temperatures. Some product sizes may not be available under this specification because heavier wall thicknesses have an adverse affect on low-temperature impact properties.

1.2 Supplementary Requirement S1 of an optional nature is provided. This shall apply only when specified by the purchaser.

NOTE 1: For tubing smaller than 1/2  in. [12.7 mm] in outside diameter, the elongation values given for strip specimens in Table 1 shall apply. Mechanical property requirements do not apply to tubing smaller than 1/8  in. [3.2 mm] in outside diameter and with a wall thickness under 0.015 in. [0.4 mm].

1.3 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

What is ASTM A333 Grade 6 pipe equivalent to?

ASTM A333 Grade 6 pipe is equivalent to several international standards including EN/DIN 10216-2, BS 3059 Part 2, and ASME SA-106.

ASTM A334 / ASME SA334 Grade 6 Chemical Compositions

Standard Grade Chemical Components (%)
C Si Mn P S Ni
ASTM A334/ ASME SA334 GR.6 ≤0.30 ≥0.10 0.29-1.06 ≤0.025 ≤0.025 /

Mechanical Tests Required

Standard Grade Mechanical Properties
Tensile Yield Elongation The Low degree of Temperature test
Strength (Mpa) Strength (Mpa) (%)
ASTM A334/ ASME SA334 Gr.6 ≥415 ≥240 ≥30 -45°

Maximum Hardness Number

Grade Rockwell Brinell
ASTM A334 Grade 6 B90 190

A334 GR.6 Impact requirements

Size of Specimen, mm Minimum Average Notched Bar Impact Value of. Each Set of Three Specimens Minimum Notched Bar Impact Value of One Specimen Only of a Set
ft·lbf J ft·lbf J
10 by 10 13 18 10 14
10 by 7.5 10 14 8 11
10 by 6.67 9 12 7 9
10 by 5 7 9 5 7
10 by 3.33 5 7 3 4
10 by 2.5 4 5 3 4

A334 GR.6 Impact Temperature Reduction:

Specimen Width Along Notch or Accrual Material Thickness Temperature Reduction, Degrees Colder
In. mm
0.394 10(Standard size) 0 0
0.354 9 0 0
0.315 8 0 0
0.295 7.5(3/4 std. size) 5 3
0.276 7 8 4
0.262 6.67(2/3 std. sze) 10 5
0.236 6 15 8
0.197 5(1/2 std. size) 20 11
0.158 4 30 17
0.131 3.33(1/3 std. size) 35 19
0.118 3 40 22
0.099 2.5(1/4 std. size) 50 28

Other Mechanical tests as follows:

l  Flattening Test One flattening test shall be made on specimens from each end of one finished tube of each lot.

l  Flare Test (Seamless Tubes) One flare test shall be made on specimens from each end of one finished tube of each lot.

l  Flange Test (Welded Tubes) One flange test shall be made on specimens from each end of one finished tube of each lot.

l  Reverse Flattening Test For welded tubes, one re- verse flattening test shall be made on a specimen from each 1500 ft [460 m] of finished tubing.

l  Hardness Test Brinell or Rockwell hardness tests shall be made on specimens from two tubes from each lot (Note 3).

l  Impact Tests One notched-bar impact test, consisting of breaking three specimens, shall be made from each heat represented in a heat-treatment load on specimens taken from the finished tube.

ASTM A334 / ASME SA334 GR.6 tubes Hydrostatic or NDT test

Each A334 GR.6 tube shall be subjected to the nondestructive electric test or the hydrostatic test. The type of test to be used shall be at the option of the manufacturer, unless otherwise specified in the purchase order.

Heat Treatment

All A334 GR.6 seamless and welded tubes, other than Grades 8 and 11, shall be treated to control their microstructure in Accor- dance with one of the following methods:

Referenced Documents

Ordering Information

ASTM ASME A/SA334 GR.6 Seamless Tubes Orders for material under this specification should include the following, as required, to describe the material adequately:


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The most important and desired changes in alloy steel are

Alloy steels are made by combining carbon steel with one or several alloying elements, such as manganese, silicon, nickel, titanium, copper, chromium and aluminum. These metals are added to produce specific properties that are not found in regular carbon steel. The elements are added in varying proportions (or combinations) making the material take on different aspects such as increased hardness, increased corrosion resistance, increased strength, improved formability (ductility); the weldability can also change.

Alloying Elements & Their Effects

Pipes, Tubes and Hollow Sections



Alloying Elements

Commonly used alloying elements and their effects are listed in the table given below.

Alloying Elements Effect on the Properties
Chromium Increases Resistance to corrosion   and oxidation. Increases hardenability and wear resistance. Increases high   temperature strength.
Nickel Increases hardenability. Improves   toughness. Increases impact strength at low temperatures.
Molybdenum Increases hardenability, high   temperature hardness, and wear resistance. Enhances the effects of other   alloying elements. Eliminate temper brittleness in steels. Increases high   temperature strength.
Manganese Increases hardenability. Combines   with sulfur to reduce its adverse effects.
Vanadium Increases hardenability, high   temperature hardness, and wear resistance. Improves fatigue resistance.
Titanium Strongest carbide former. Added to   stainless steel to prevent precipitation of chromium carbide.
Silicon Removes oxygen in steel making.   Improves toughness. Increases hardness ability
Boron Increases hardenability. Produces   fine grain size.
Aluminum Forms nitride in nitriding steels.   Produces fine grain size in casting. Removes oxygen in steel melting.
Cobalt Increases heat and wear   resistance.
Tungsten Increases hardness at elevated   temperatures. Refines grain size.

ASTM A335 Chrome Moly Pipe

ASTM A335 Pipe (ASME S/A335, Chorme-Moly) is a seamless ferritic Alloy-Steel Pipe for high temperature service.

ASTM A213 Tubes

ASTM A213 covers seamless ferritic and austenitic steel boiler,Boiler Tube, and heat-exchanger tubes for high temperature services, designated Grades T5, TP304, etc.

【H】 Ceramic lined pipe

Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.

【H】 Cast basalt lined steel pipe

Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.

【H】 Ceramic Tile Lined Pipes

Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.

【H】 Rare earth alloy wear-resistant pipe

The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.

【H】 Tubes Erosion Shields

Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.

【H】 ASTM A213 T91 Alloy Tube

The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.

Ni-Hard Wearback Pipes Ni-Hard Wearback Pipes