Doorsheets for Tanks?

[collism]

Is there a requirement for size & reinforcement for cutting doorsheets in tanks? I have looked through API 620, 650 & 653 and have not found anything except for distance from welds & HAZ. I am looking at cutting a 6 ft x 8 ft doorsheet in the second shell ring of a 144 ft diameter by 40 ft high atmospheric storage tank.

 

[JoeTank]

There is no API requir4ment for the doorsheet size, You pick the size based upon the type of work that will be passing thropugh the opening.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[BJaffa]

Door sheet rules for weld spacing and joint design are the same as used for shell plates. Specific rules for cutting in existing tanks are found in API 653. Examining the base metal prior to cutting can prevent latter problems. Experienced contractors can suggest reinforcing the opening and methods to minimize shrinkage during reconstrucion.

 

[JoeTank]

Collism,
My apolgies for an incomplete answer. I did not read your post closely. The use of reinforcement is determined by the repair contractor. The sizing and layout of the stiffeneing members is usually based on their successful experience, not calculations. Don't be shocked if no framing is used as I doubt it would be used by most contractors. If stiffened, I would expect to see 6 or 8 inch channels being used as a frame around the opening. Whether stiffend or not, you will see some amount of distortion due to weld shrinkage. This is an issue of tank repair artistry, not science. Good welding is not enough in this case, so select your contractors wisely. Get references on similar projects if unsure.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com