Telltale Hole Location API 650 Tank

[marcleblanc12]

Does anyone know of a minimum distance for a telltale hole to the edge of a repad for API 650 tanks?

All I can see in the code is along the horizontal center line. There has to be a minimum edge distance though. There's no way you can't put them right on the edge of the repad.

 

[IFRs]

You could use the manway repad as one guide - for a diamond shaped repad, figure 7.7 shows the telltale on the circumference of the round repad circle but I don't know if this was deliberate.

For round repads, I usually split the distance from the neck weld to the edge of the plate, as shown in API 653 figure 9.14.

 

[valleytank]

Never put them too close to the edge. You will get some deformed whatever-NPT hole after the welding is complete and the repad sucks back to the curvature of the tank. Do what IFRs suggested. If the repad is split along the centerline offset your weepholes down/up 2"/6t off that weld centerline.