Dear Santosh:
Of course you should refer to your project specifications...
BUT
There is an option (providing your client has a good engineering sense)
If you pipe is not austenitic stainless steel or Ni-based, you may
carry out stress relieving heat treatment on any of the welds and you
will be OK.
The main reson for specifying a minimum value for proximity of the
welds is that when welds are close to each other, the residual stress
build up will jeopardize the integrity of that particular section of
the pipe. When you carry out PWHT, the trouble-maker will go home and
you are safe. of course the turbulence caused by weld penetration into
flow is another issue but not a major one.
Best of luck
Ramin Kondori
IWE AT 0070