TDW PIG-SIG V, Operating And Maintenance Instructions Manual

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Section IV – Pipeline Under Pressure
1.0 Continued
1.2 Welding Instructions
A. Clean all weld edges thoroughly. Remove all
paint, dirt, rust, oil, etc., from the weld areas.
B. Position the nipple so that it is on the top
centerline of the pipe and perpendicular to the
surface of the pipe.
C. If moisture is on the line, dry the area where the
nipple will be located to remove the moisture
before installation is started. This is important in a
high-moisture atmosphere.
NOTE :
Weld procedures and welders should be qualified to current
API 1104, API 1107, or ASME Section IX.
Low hydrogen electrode AWS-E-XX18 is recommended for
use with TDW fittings. The use of low hydrogen electrodes
is specifically recommended by certain welding specialists
when the nipple is to be welded to pipelines operating in a
high moisture area and/or a temperature below 50-degrees
Fahrenheit. Use of AWS-E-XX18 electrodes helps avoid
cracks that can result from stress produced during
solidification of weld metal and help avoid hydrogen-
induced cracking. Consult the manufacturers of such
electrodes for proper care and use.