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Welding Inspection & Metallurgy API ICP Self Study Notes

API ICP Self Study Notes

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Preheating, for our purposes, is defined as heating of the weld and<br />

surrounding base metal to a predetermined temperature prior to the start of<br />

welding. The primary purpose for preheating carbon and low-alloy steels is to<br />

reduce the tendency for hydrogen induced delayed cracking. It does this by<br />

slowing the cooling rate, which helps prevent the formation of martensite in<br />

the weld and base metal HAZ. However, preheating may be performed for<br />

many reasons, including:

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