"tan tan" - What does it mean when used for vessel dimensions? 7

[CV70]

I got vessel dimension e.g. 4600 Dia x 22300 tan tan (mm)

What does "tan tan" stand for?

Apologizes for this simple question - I am not a native English speaker ;-)

 

[SNORGY]

It is (unofficially):

"Tan-To-Tan" = "Seam-To-Seam" + 4 inches

The "Tan" is the tangent point where the curvature of a formed head starts. The "Seam" is the point at which the head is welded to the shell; it is common for there to be a 2" straight length beyond the "Tan" for this purpose.

Regards,

SNORGY.

 

[zdas04]

CV70,
There is nothing to apologize for. A large number of native English speakers (myself included) did not have a clue what tan-to-tan means. Thanks SNORGY for educating all of us.

David

 

[bimr]

Tan-tan is an abreviation for the length of a vessel from tangent line to tangent line. The tangent line is the point where the tank head is welded to the tank cylinder.

Tangent Line: Refers to the point of contact (tangency) between the cylinder and the knuckle portion of the vessel head. The distance from the tangent line on one head to the tangent line on the opposite head is known as the straight side, or tangent-to-tangent (T/T).

http://www.prentex.com/glossary.php

The depth of tank heads will vary with the diameter of the head. You would have to visit a head manufacturer's catalog to determine the height of a head. There are also different types of heads: dished, spherical, etc.

 

[CV70]

Snorgy,
Bimr,
thank you for this very good explanations and extremely fast replies.

Zdas04,
thanks for the encouraging words. Makes me feel better.

I very am impressed about this forum and its members!
Regards

Christian

 

[europipe]

Snorgy and Bimr,
What I learned was:
The tangent line is the line where the radius of the tank
passes into the straight cylinder.
That is mostly not the weld seam.
"Tangent Line: Refers to the point of contact (tangency) between the cylinder and the knuckle portion of the vessel"That is right bimr.
The haed mostly has a straight piece.
(And please excuse me too for poor grammar,English is not my native language either)

Greetings

 

[bimr]

This head manufacturer states that the straight flange portion of the head measured from the tangent line to the edge of the head is an industry standard 1-1/2”, but this may vary slightly by manufacturer or project.

http://www.brightontruedge.com/types.htm

Further information can be obtained by reviewing this ASME course:

http://files.asme.org/asmeorg/Governance/Volunteer/CareerSeries/9667.pdf

 

[davsy]

Be careful with the assumed 2" straight flange. As Bimr has pointed out above a lot of manufacturers use 1.5" for the straight flange and that has certainlybeen my experience over the last too many yers.

 

[moltenmetal]

Tan to tan dimensioning is used in part BECAUSE you don't know the straight flange length until the vessel is designed. Depending on the vessel size, the vessel designer may use a head (of varying dimension as davsy has pointed out), or if the vessel is small enough they may use a pipe cap- definitely different straight flange length on those!

 

[JohnGP]

Yes, sometimes it is better to work with S/S (weld Seam-to-Seam) dimensions - then there is a chance of keeping to standard plate widths (lower cost), unless there are special process or other reasons for specifying something different.

Cheers,
John

 

[hockchong]

Guys,
Don't forget that for Hemi Head vessel, the situation is totally different. S/S > T/T. It will required both thickness to determine the T/T.

HC