Re: [MW:16563] Re: HOW TO DISTORTION CONTROL-JOINING TO 4" 40 SCH PIPE WITH 4" ELBOW (SS-304L) FOR LNT -FERTILISER PROJECT

 

Mr. Ashis,

Answers for the quires as follows:

 

1) Pipe (SS-304L) to Elbow (SS-304L) (Single V Grrove Joint)

2) Pipe Size is 4" 40 Sch & Elbow size is 4" .

 

Query:-

How to control distortion:-

 

     a)     One set of Pipe & elbow is rejected from my Side Caused by Distortion (i.e It got offset)

Pipe thickness being 6.02 mm, the distortion control is limited with normal TIG process. Pulsed-TIG

welding process with better control on heat input will definitely help you to arrest the said distortion and

keep it  within  ½⁰ (degree) or less which is acceptable. Over that, proper tack welds should help.

 

     b)     Weld layer/ripples are not as per Expectation Limit of TPI

 

That happens with any SS electrode. Thickness being only 6.02mm you could have gone with TIG process        itself (of course with a WPS) , otherwise use 308L -17 type  (special coated electrode) which will give a

uniform, smooth and fine bead ripple factor comparatively. Similar type of  electrodes are available as

E 316L-17 also.

 

     c)      beacause one end of Pipe is coonected to  Elbow (Other end of Elbow is coonected to 4"Gt Valve)& other end of pipe is coonected to 40" GT Vavle. It is very difficult for welder to weld in this position .(Weld Ripples /String tech is failed caused by uncomfort zone of welders) Distortion control is far ahead…….

 

Sorry, unable to understand. Is it a branch connection to 40 " gate wall-pipe assembly?  Whatever the position

may be, welder should practice in 6G, to get the joint done to the satisfaction of the job and TPI.

Comfort of the job i.e., quality of welding is more important than the welder's comfort.

 

Pulsed TIG  gives a very low amount of heat input (because of the nature of the process) compared to SMAW

or normal TIG process, PT  is very ideal and would give you best finish with proper parameter selection right

from 0.50 mm thick and also preferred for  root runs in heavy wall and higher dia. Pipes.

.

f) To hide weld ripples from TPI (I instructed Grinder men to do grinding on weld ripples ).TPI had objection on this?

But ASME code does not restrict on Grinding on weld ripples

g) What kind of tests required here?  TPI is inspection RT , because there is visual examination of Weld repair (I have commited beacasue of visual examination).

 

Since x-ray is being done, surface grinding is not allowed and bead-ripples are to be maintained as such. Sometimes it gives notch effect if not done properly or surface tension which is not desirable for SS.

In many automobile fabrication units, grinding is strictly prohibited  and few TPI agencies do not permit

grinding for PQR & WPQ tests also.

                                                                                                                                          

How to do RT in Shop floor , when 40 " Gt valve is there & Pipe + Elbow is erected ­­­

j) is there any need to do UT?

 

What is the code of welding ?. X-ray can be done if the joint is on the floor. Even it is in the rack, you can

provide, scaffolding to take your equipment  up, to do the radiography.

X-ray is done mostly in the late evenings in all workshops, when the workers are not working  and you

have to provide safety arrangements by cordoning off that area till you complete the x-ray. It should not be a

difficult task. But take proper precautions for human-safety.

UT is your choice, but not mandatory as per the ASME sec. IX code. Initial UT may help to remove the

defects if any and save you time & cost.  Also Check your QAP for further details..

 

k) TPi is rejected & had gone out of City ?

l ) I m fearing , beacause its nearly about 1 Crore estimate Size Valve ? (There are 2 valves in this project)

s as follows:

 

There is nothing to fear, in the welding & fabrication, if the procedure is followed fully, and doubts if any

could be clarified through proper channels prior to taking our  own decisions..

Sridhar.

 

 

Technically Virtuous :- "ORBITAL TIG Welding M/c "
 

On Wed, Jan 16, 2013 at 2:58 PM, Ashish Pathrabe <darkash6633@gmail.com> wrote:

Dear Experts,

We got fertiliser Project from Lnt:-

Following are welding details:-(Root gap welded by TIG & remaning by SMAW)

1) Pipe (SS-304L) to Elbow (SS-304L) (Single V Grrove Joint)

2) Pipe Size is 4" 40 Sch & Elbow size is 4" .

 

Query:-

How to control distortion:-

a) One set of Pipe & elbow is rejected from my Side Caused by Distortion (i.e It got offset)

b) Weld layer/ripples are not as per Expectation Limit of TPI

c) beacause one end of Pipe is coonected to  Elbow (Other end of Elbow is coonected to 4"Gt Valve)& other end of pipe is coonected to 40" GT Vavle.

d) It is very difficult for welder to weld in this position .(Weld Ripples /String tech is failed caused by uncomfort zone of welders)

e) Distortion control is far ahead..(Completed bend out).

f) To hide weld ripples from TPI (I instructed Grinder men to do grinding on weld ripples ).TPI had objection on this?

But ASME code does not restrict on Grinding on weld ripples

g) What kind of tests required here?

h) TPI is inspection RT , beacause there is visual examination of Weld repair (I have commited beacasue of visual examination).

i) How to do RT in Shop floor , when 40 " Gt valve is there & Pipe + Elbow is erected /attached to such a big 40" Gt Valve.

j) is there any need to do UT?

k) TPi is rejected & had gone out of City ?

l ) I m fearing , beacause its nearly about 1 Crore estimate Size Valve ? (There are 2 valves in this project).

m) I am answerable to managment . Pls guide

& Help Out.........

 

With Regards,

Ashish P

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