API 650 - Telltale Hole in Reinforcement Pad

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Shavessels Associate Join Date: Oct 2010 Posts: 31	API 650 - Telltale Hole in Reinforcement Pad 05/04/2012 2:25 PM
	Hi All As per API 650, telltale hole in Reinforcement pad shall be located substatially on the horizontal centerline. Could you please explain the reason? What will be the effect if the tellhole located at other locations? Pls ans.
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Abdel Halim Galala Guru Join Date: Feb 2007 Location: Cairo, Egypt Posts: 1733 Good Answers: 247	#1 Re: API 650 - Telltale Hole in Reinforcement Pad 05/06/2012 1:56 AM
	As per API 650, there is one 6 mm (1/4") telltale hole in reinforcing plate, on horizontal centerline to allow breathing of air pockets may be located between reinforcing pad and tank wall due to expansion and contraction of these air pockets especially during welding. And the horizontal location at centerline is preferred because it is located at the middle area of whole reinforcing pad between upper and lower halfs of pad to facilitate good breathing during hot and cold conditions. ........................................... __________________ It is better to be defeated on principles, than to win on lies!
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Shavessels Associate Join Date: Oct 2010 Posts: 31	#2 In reply to #1 Re: API 650 - Telltale Hole in Reinforcement Pad 05/06/2012 7:36 AM
	Hi Mr. Abdel Halim Galala Why this reason not applies to Piping RF pad(B31.3 says that A vent hole shall be provided at the side (not at the crotch) of any pad or saddle to reveal leakage in the weld between branch and run and to allow venting during welding and heat treatment) and Pressure vessel RF pad (ASME Sec VIII Div.1)? If I'm wrong correct me pls. Regards.
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Siva Ramachandran Participant Join Date: Dec 2015 Posts: 1	#3 In reply to #1 Re: API 650 - Telltale Hole in Reinforcement Pad 12/19/2015 7:25 AM
	If it is so, why don't we make telltale in the vertical central line of the pad which also equally separate the left and right side of the pad. In my point of view, in horizontal central line, load will be zero. As we have tensile load on the top and compressive load on the bottom portion of the RF pad, it may propagate crack from the telltale hole if it is overloaded by external nozzle distortion
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