Earl and the Aboveground Storage Tank Forum for fuel tanks, plastic tanks, fuel oil storage tanksWelcome to the aboveground storage tank forum, a bulletin board dedicated to tanks, fuel tanks, plastic tanks, fuel storage tanks, and above ground storage tanks (AST) API650, API653 & UL142 aboveground storage tanks (AST) and chemical plastic tanks. Remember the forum is made up of volunteers from experts to beginners. Unfortunately, we cannot allow free commercialism that promotes products, services, or sites.
 
Sponsored by:
Spirax SarcoIndustrial Training School - Instrumentation
Contact us about advertising
Earl   AST Forum  

Stephen H on Telltale hole

By: Stephen H 
Date: Thursday, January 26, 2006
Time: 12:00:00 AM

I've seen two different uses. On storage tanks, it is a hole in the repad of a nozzle. If the nozzle welds (or plate) start leaking, it will show up at the tell-tale hole. I guess this avoids trapping product when you try to work on a tank as well. The same hole is typically used to air-pressure-test the repad for leaks. If a nozzle is stress-relieved, it would also serve to vent the area between the repad and shell. In the design of a repad, it is assumed that the shell has pressure against the inside of it. If the area between the repad and shell is allowed to pressurize the same as inside the tank, the tank wall in that area no longer has a net pressure against it. It would theoretically try to flatten into a chord, transferring more force into the repad. At the ASME Section VIII class a while back, they referred to tell-tale holes as small holes drilled almost through the walls of a pressure vessel. The idea being that if uniform internal corrosion exceeds a certain amount, it will start leaking at the holes, and give an indication, rather than progressing on to a possible catastophe. I don't know how commonly these are used.



Published on ast-forum.com

Industrial Training School - Maintenance

School_Shield.jpg Industrial Training School

 


Maintenance Mechanic


Industrial Training School is offering this maintenance training course for perspective maintenance mechanics or maintenance mechanics in-training.  This maintenance mechanic training course is meant for students that have some experience as a maintenance mechanic and desires to improve their knowledge to benefit their job and place of work.

Maintenance Systems


This Maintenance Systems training course for covering fundamentals of maintenance practices for industrial, facilities and building maintenance programs and is meant to aid clerks, supervisors or administrative personnel in maintenance. 

Sponsors
Spirax SarcoIndustrial Training School - Steel Making Tutorial
Want to Advertise on the AST Forum
Confidentiality, Disclaimer & Policy
AST FORUM
© 2001 to Aboveground Storage Tank - AST Forum, All Rights Reserved.
Valid XHTML 1.0 Transitional