Field Engineers: Tie-In Spools

Compressibility of the gasket material that is to be taken as standard. After compression, the strength of the gasket to hold the fluid under specified pressure without leak over a period is going to be the final requirement.

Perhaps look for data of the manufacturers in the same product line and they will give reasonable amount of details for their selection criteria.

Does choosing the method of installing the gasket in the flange affect the gap to be considered ? i mean it can be either fitted inside the groove and then the flanges are aligned before hydratighting

or the flanges can be first aligned by bolts spikes...etc then after aligning them, the top bolts or spikes are removed and then the gasket is slipped by the diver in between the flanges. But in this case and correct me if i am wrong, the gap to be considered should be at least the height of the gasket from the raised face of the WN flange to the raised face of the swivel flange.

Does one have the flexibility of using any method of the stated above, or are there constraints to be considered.

Gasket material forms a seal by flowing into the gaps and under pressure becomes harder to withstand pressure. All this goes with proper calculation for the requirement such as pressure and the gasket material. The gap sets the final pressure on the gasket and that should be comparable with that of the pipe fluid pressure or vacuum level else the gasket is either pushed out or is shucked in from its place in time.

Thanks Shyam. you were very informative.

i agree with you but the thing is that i was talking from a construction point of view

while you were talking from a design point of view. Obviously all should lead to what you are saying, but if you consider a bigger gap in the beginning inorder to install the gasket (slip it, fix it in the groove) then apply bolt tensioning and crush it to the final gap you mention, you might either not get the results you are hoping for or damage the flanges or the bolts (if the initial gap you consider is bigger than what is supposed or you might (the diver) find difficulty inserting it in the groove if the gap is smaller than the gasket height.

My question initially was what is the gasket gap that you consider when installing the spool so that after you bolt tension the flanges you get the final acceptable design gap.

i dont know if i am making sense in what i am saying....i guess anyone who worked in spool installations knows what i am talking about.

would really appretiate all your inputs from the design and construction point of view.

cheers.

not my chosen speciality, but I've seen plenty of blow-out-preventors and wellheads assembled and the majority of those are sealed by metal-to-metal seal technology where the metal ring seal is embedded into both flange faces and then bolted down tight....very tight. Some of these seals are good for 5,000 PSI and some as much as 15,000PSI -

try www.cameron.com

alternative name might be ingram cactus...national oilwell....(www.nov.com)

Hope this helps

The pipe manufacturer will be the best one to provide this information. I work in the water/wastewater industry and we typically see an 1/8" allowance for gaskets.

If you are connecting to an existing pipe you will need to be sure the connection is possible. Many times trying to fit a flanged fitting into an existing line is virtually impossible.

Does choosing the method of installing the gasket in the flange affect the gap to be considered ? i mean it can be either fitted inside the groove and then the flanges are aligned before hydratighting

or the flanges can be first aligned by bolts spikes...etc then after aligning them, the top bolts or spikes are removed and then the gasket is slipped by the diver in between the flanges. But in this case and correct me if i am wrong, the gap to be considered should be at least the height of the gasket from the raised face of the WN flange to the raised face of the swivel flange.

Does one have the flexibility of using any method of the stated above, or are there constraints to be considered.