SECTION II M747 TRAILER FRAMES

TB 9-2510-242-40

SECTION II M747 TRAILER FRAMES

3.1 WELDING PROCEDURES

3.1.1 T-1 Steel. "T-1" (formerly a United States Steel trademark) is a high strength quenched and tempered alloy steel

which conforms to ASTM A514 specification requirements. The T-1 steel alloy composition and heat treatment combine

to produce favorable mechanical and physical properties such as:

high yield and tensile strength:

good toughness:

corrosion resistance:

weldability.

In order to maintain these properties, proper welding procedures and cautions must be followed. T-1 steel welds on the

M747 trailer should not be subjected to post-weld heat treatment, which may cause loss of material strength, loss of

toughness, and stress rupture cracking.

3.1.2 Pre-Welding Preparations. Check ambient air temperature in work area. Welding should not be done in

temperatures below 32 degrees F (0 degrees C). If ambient air temperature is below 32 degrees F, a heated structure is

required to maintain temperature surrounding the weld repair area at 32 degrees F or higher. Support and secure

damaged frame members and joints prior to welding according to the following procedure.

Remove structural load from the joint(s). Use jack stands or other cribbing to safely support both sides

of the damaged area(s). Place other supports as required to prevent frame movement during inspection

and welding preparation.

Align members of damaged joint(s). Ensure that broken or replacement pieces of the segment touch

each other. Measure type, size and extent of each damaged weld that is to be repaired. NOTE: Repair

welds should be of the same size and type as the original weld joint.

Inspect cracks. Determine the extent of weld or base metal crack(s) by use of dye penetrant inspection or

any other equally positive means.

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