American Petroleum Institute

Rolled Shapes with Improved Notch Toughness - First Edition; Effective December 1, 2002
 N SPEC 2MT2

Annotation

This specification covers rolled shapes (wide flange shapes, angles, etc.), having a specified minimum yield strength of 50 ksi (345 Mpa), intended for use in offshore structures. Commonly available Class A, Class B, and Class C beams refer to degrees of fracture criticality as described in section 8.1.3 of API RP 2A, with Class C being for the least critical applications. For special critical applications, Class AAZ shapes may be specified, by agreement, using supplement S101.

Supplementary requirements are provided for use where additional testing or additional restrictions are required by the purchaser. Such requirements apply only when specified in the purchase order.

When the steel is to be welded, a welding procedure suitable for the grade of steel and intended use or service is to be utilized. For the purposes of welding procedure qualification under AWS D1.1, until AWS cites this specification, use the following:

a. Matching filler metals (AWS D1.1, Table 3.1) shall be as for Group II.

b. Preheats (AWS D1.1, Table 3.2) shall be as for Category B (or Category D for class A-QST herein).

c. Matching weld toughness (AWS D1.1, Tables C4.2 and C4.3) shall correspond to Class A, B, or C herein.

Alternative preheats (AWS D1.1, Annex XI) may also be used to advantage.

When heat straightening, hot or warm forming, or postweld heat treatment above 1050°F (565°C) is anticipated for Class A shapes produced by methods other than hot rolling, controlled rolling, normalized rolling, or normalizing, supplement S9 should be invoked.