separates the top of the rail head and bottom surface of the straightedge
at both ends.
3.1.3
Placing of Molds
Attach the molds to the rails, centered over the joint, and seal the molds
to the rail with luting material according the welding kit manufacturer's
instructions. Handle the luting material, a mixture of clay and sand, so
that none is introduced into the weld chamber. Align so that the
centerline of the mold coincides with the centerline of the gap. Install
the tapping plug or discs in the crucible and pour in the prescribed amount
of thermite mixture.
3.1.4
Preheating Rail Ends
In accordance with the manufacturer's instructions and recommendations.
3.1.5
Ignition of Thermite
Follow manufacturer's instructions and recommendations.
3.1.6
Mold Removal
Follow manufacturer's instructions.
3.1.7
Finishing
Follow manufacturer's instructions and recommendations. No finishing is
required on the web and base of rail. Perform final grinding when the weld
and rail have cooled to ambient temperature. Under no circumstances shall
a cutting torch be used to remove excess weld metal.
3.1.8
Joint Records
Provide a record of the date and location of each weld made. The record
shall also include the rail type, size, thermite kit manufacturer's name,
and thermite weld portion batch number. Also, provide a record of the
nondestructive test date and acceptance date.
3.2
INSPECTION AND TESTING
3.2.1
Visual Inspection
Each welded joint by shall be inspected by the Contractor after removal of
the mold and grinding or removal of excess metal. The inspector shall pay
particular attention to surface cracking, lack of fusion and other surface
irregularities. The Contractor shall correct or replace all defective
welds at no additional cost to the Government. The method of correction
shall be approved by the Contracting Officer.
3.2.2
Nondestructive Inspection
Inspect each welded joint by ultrasonic tests using the method of
inspection and acceptance as prescribed in MIL-STD-1699. The Contractor
shall correct or replace all defective welds at no additional cost to the
Government. The method of correction shall be approved by the Contracting
Officer. All repairs to defective welds shall be ultrasonically inspected
by the Contractor using the method of inspection and acceptance as
prescribed in MIL-STD-1699.
SECTION 05652N
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