Expanded Tube Ends 2

[alexx]

Hello,

I have an application where we are expanding tubes into a boxed header. The fluid through the tubes is natural gas. I have a couple of questions that hopefully someone can help. The header and tube circuits are designed to ASME SECTION VIII.

(1) For grooved header holes, what is the recommended groove design (depth, width)? Is there some industry or code standard that is commonly used?

(2) For natural gas applications, Section VIII requires that the expanded connection be given a seal weld. What size of seal weld is required. I couldn't find a requirement in the ASME code.

Thank you,

Alex

 

[deanc]

See ASME SecVIII Div1 Appendix A also contact the tube roll
Manufs. Airetool,Elliott,Thomas Wilson for more general info.

 

[UKCats]

Are you expanding tubes like a heat exchanger tube sheet??? If so, TEMA Ed. 8 gives groove depth, width, etc. RB-7.44 and C-7.44. page 71.

 

[toto37]

alex

in a frist place you has to now that there is no expansion joint for a heatexchangers and one for a high pressure boiler eaven if in this case is working with natural gas at high pressures ,you have to make the rigth wall reduction for a expansion joint and you can be sure that is no going to leake not even if you uses this in a high or low pressure equipment ok?

now speaking of serratios or grooves a hole with out it is going to seal a 100 % but there is no 100 % holding power but if you only install a groove with the falowing dimentions 1/8" wideth by 1/32" deep gets a 139 % of holding power but if you install 2 grooves you gets 153 % holding power this means that with two grooves you gets 53% of holding power more then a hole with out grooves we make test for this values in a cold working ,and the reason of all this conditions is be cause the expanded joints are a frictions joints where the forces that handles can be increased if the surface in contact are but rough keeping the values as i tell you ahead , any way i have beening doing this for more then a 25 years an let me tell you there is not much write information of this matters ok?

now there is some factors you have to take care, for example the condition of surface of the tube or the tubesheet, in the case of the tube it has to be a 130 m.i. you have to keep this value as a maximum in the area of expansion of the tube, and in the case of the tubesheet is has to be no more then a 200-300 m.i..

now in the other case you have to take care of the hardness of each one of the materials, for example in the case of the tube the maximum value is a 130 bhn or less, and in the tubesheet is 142 to 180 bhn, this means that never can be harder the tube then the tubesheet is clear?


if you have any doubt give me a call by e-mail at heatexg@latinmail.com i have doing a mayor studies of the efects of the forces involved in the expanded joints,
an for the welded seal you can make them like the power boiler says deep no more then the tube tickness an heigth no more then the diameter of the tube an with 45° rigth now i dont have the exact page of this manual but let me loking for an i send that to you let me now your e-mail

toto37

 

[bmoorthy]

Use 7-3-6-3 X 0.4 deep. That is start groove at 7mm from front of the tube sheet plate, use 3mm wide groove leave a gap of 6mm and again a groove, 3mm wide and 0.4 mm deep. This config is generally used in Heat exchangers, including Air fin Coolers. TEMA, API 660, API 661 can be refered. In the recommeded practice of TEMA type of joint selection is briefly touched upon. Chemical Engineering Handbook Perry also gives some guideline.

When Seal welding is specified, size of fillet is not a significant factor as far as design is concerned. One has to specify the dimension of seal weld for the purpose of production/fabrication planning. 1mm to 2mm fillet is good enough depending on the thickness of the tubes.

ASME Appendix A also gives some guidelines.

 

[alexx]

Thank you everyone for posting and helping on this issue.


Alex

 

[chicopee]

If this note is note tool late, make sure tubes are expanded w/ a 4 roll tube expander and not w/ a 3 roll type.

 

[qcwelder]

Our company is looking for someone who can do calculations and drawings for a gas cooler section and we are having trouble finding someone who can? can anyone help us?
Thank you.

 

[GenB]

I have a few contacts,
email info to generalblr1@netzero.net
ER