PREHEATING 2

[Alirashid]

API 650 code tank.
Anchor chair pad (thickness 15mm) to be welded with anchor chair top plate/comp plate (thickness 35mm) fillet weld with Material P1-to-P1. Is there any requirement to preheat,if yes then what will be the preheat temperature?

 

[metengr]

Yes, the minimum preheat should be based on the thicker of the two components, 65 deg C.

 

[ll23]

You should take on count this paragraph,
"7.2.1.3 No welding of any kind shall be performed when the surfaces to be welded are wet from rain, snow, or ice;
when rain or snow is falling on such surfaces; or during periods of high winds unless the welder and the work are
properly shielded. Also, preheat shall be applied when metal temperature is below the temperature required by Table
7.1a and Table 7.1b. In that case the base metal shall be heated to at least the temperature indicated in Table 7.1a
and Table 7.1b within 75 mm (3 in.) of the place where welding is to be started and maintained 75 mm (3 in.) ahead of
the arc."

 

[Oscarvs]

According API 650, Table 7.1a, Minimum Preheat Temperature (MPT), if 32mm < Thickness <= 40mm; then MPT is 10°C for Material Groups I, II, III & IIIA and MPT is 40°C for Material Groups IV, IVA, V & VI.
Paragreph 7.2.1.3 shall be take count.

Material Groups are indicated in Table 4-4a.