Standrad spacing between pipes pluged on a manifol

behanzin,

There are a number of issues that must be considered in the answer to this specific question.
One issue relates to branches that will have no Flanged joints for Valves of other in-line items. The another issue relates to branches that will have Flanges for Valves and or other inline items such as Flow Meter Instruments. You did not define if your situation will or will-not have Flanges.
A third issue is the possibility of Insulation on these Branches

So, minimum spacing might be as follows:

#1 No Flanges/No Insulation - Outside to outside of Branch pipe = Not less than the 4 times the wall thickness of the Header Pipe (4T). This will reduce overlap of the Heat Affected Zone of the Branch pipe weld. Some Client or Company Standards may require more than 4T.

#2 No Flanges/with Insulation - Outside to outside of Branch pipe = 2 times the Insulation thickness plus one inch.

#3 With Flanges, with or without Insulation - If Flanges are staggered then the Branch spacing would be the same spacing as normal piping in a Pipe Rack.

#4 With Flanges, with or without Insulation - If Flanges are not staggered then the Branch spacing needs to be based on the Flange outside diameters plus Handwheel (or valve operator) clearances.

Then your case is #2

#2 No Flanges/with Insulation - Outside to outside of Branch pipe = 2 times the Insulation thickness plus one inch.