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Building Design and Construction Handbook - Merritt - Ventech!

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STRUCTURAL STEEL CONSTRUCTION 7.13<br />

FIGURE 7.3 Effective throats of fillet <strong>and</strong> groove welds.<br />

Welding Procedures. The variables that affect the quality of a weld are controlled<br />

by welding procedures that must be approved by the structural engineer. Specification<br />

AWS D1.1 contains several prequalified welding procedures, the use of<br />

which permits fabricators <strong>and</strong> erectors to avoid the need for obtaining approvals<br />

for specific routine work. Where unusual conditions exist, the specification requires<br />

that formal documentation be submitted for review <strong>and</strong> approval.<br />

Base-Metal Temperatures. An important requirement in production of quality<br />

welds is the temperature of base metal. Minimum preheat <strong>and</strong> interpass temperature<br />

as specified by the AWS <strong>and</strong> AISC st<strong>and</strong>ards must be obtained within 3 inches of<br />

the welded joint before welding starts <strong>and</strong> then maintained until completion. Table<br />

7.7 gives the temperature requirements based on thickness (thickest part of joint)<br />

<strong>and</strong> welding process for several structural steels. When base metal temperature is<br />

below 32�F, it must be preheated to at least 70� <strong>and</strong> maintained at that temperature<br />

during welding. No welding is permitted when ambient temperature is below 0�F.

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