4。2。 Use of other materials shall be by agreement。

5。2Tensile Test Requirements

Tensile test specimens shall be removed from a test coupon (TC) after the final heat-treatment cycle。

Perform tensile tests at room temperature in accordance with the procedures specified in ASTM A370 or ISO 6892-1。

Perform a minimum of one tensile test。 All yield strengths shall be determined using 0。2 % offset method。 The results of the tensile test(s) shall satisfy the applicable material specification requirements。

If the results of the tensile test(s) do not satisfy the applicable requirements, two additional tests on two additional test specimens (removed from the same TC with no additional heat treatment) may   be

performed in an effort to qualify the material。 The results of each of these tests shall satisfy the applicable requirements。

5。3Service Compatibility

All process-wetted parts, metallic and nonmetallic, and lubricants shall be suitable for the commissioning fluids and service when specified by the purchaser。 Metallic materials shall be selected so as to avoid corrosion and galling, which would impair function and/or pressure containing capability。

Selection of elastomeric materials for valves intended for rapid gas decompression service at pressures of Class 600 and above shall address the effect of explosive decompression。

5。4Forged Parts

All forged material(s) shall be formed using a hot-working practice and heat treatment that produces a forged structure throughout the material。

5。5Composition Limits

The chemical composition of carbon steel pressure-containing and pressure-controlling parts shall be in accordance with the applicable material standards。

The chemical composition of carbon steel welding ends shall meet the following requirements。

—The carbon content shall not exceed 0。23 % by mass。

—The sulfur content shall not exceed 0。020 % by mass。

—The phosphorus content shall not exceed 0。025 % by mass。

—The carbon equivalent (CE) shall not exceed 0。43 %。

The CE shall be calculated in accordance with the equation below: CE = % C + % Mn/6 + (% Cr + % Mo + % V)/5 + (% Ni + % Cu)/15

The chemical composition of other carbon steel parts shall be in accordance with the applicable material standards。

The carbon content of austenitic stainless steel welding ends shall not exceed 0。03 % by mass, except for stabilized material in which case a

carbon content of up to 0。08 % by mass is permissible。

The chemical composition of other materials shall be established by agreement。

5。6Toughness Test Requirements

Carbon, alloy and stainless steel (except austenitic grades) for pressure-containing parts in valves with a specified design temperature below –20 °F (–29 °C) shall be impact-tested。 The test method shall be the V-notch technique in accordance with ASTM A370 or ISO 148-1。 When using ISO 148-1, a striker with a radius of 8 mm shall be used。 Refer to ISO 148-1 for further details。

NOTE Design standards or local requirements can require impact testing for minimum design temperatures higher than –20 °F (–29 °C)。

A minimum of one impact test, comprised of a set of three specimens, shall be performed on a representative test bar of each heat of the material in the final heat-treated condition。

Test specimens shall be cut from a separate or attached block taken from the same heat, reduced by forging where applicable, and heat treated to the same heat treatment, including stress relieving, as the product materials, except that it is not necessary to retest pressure-containing parts stress relieved at or below a previous stress-relieving or tempering temperature。 The impact test shall be performed at the lowest temperature as defined in the applicable material specifications。