Pipe Thickness and Branch Connections

What exactly do you mean by "thickness of header"? Do you mean the pipe Ø? If so, it's derived from the volumetric flow rate and maximum allowable fluid velocity through the pipe.

"in case of using ready made fittings like as Tee, Weldolet, extruded branch, ... etc., no nozzle reinforcement calculations are needed."

I'd be careful with that. I was trying to purchase a 45 degree lateral connection from a vendor when we found out that it was simply two pipe segments welded together. I checked their spec sheets and they only conform to ASTM standards (although when I asked about B31.3 they said they conform to that and API 570???). I asked if they had done any calculations to show that this was B31.3 and they told me that I would need an engineer to do that.

In other words, this was two pieces of pipe welded together by rule of thumb engineering. For my 14" x 14" lateral, we had to get a local contractor to modify it with a repad to meet ASME standards.

But for the original question, use ASME B31.3 paragraph 304. Read through all of it and you will go over straight pipe and branch pipes.

The 45^o lateral which consists of two pieces and connected together by welding is not considered a ready made fitting, therefore there must be a reinforcing calculations to be carried out as per your piping code.

That lateral which consists of two pieces, can be produced under any code, but you have to verify all design calculation and the reinforcement compensation as per your ASME piping code (B31.1 for Power Piping , B31.3 for Process or Refinery Piping, B31.4 for Liquid Pipeline & B31.8 for Gas Pipeline).

Important note. Proceeding the calculations as per ASME B31.3 can be recommended to be used in lieu of other piping codes in such a plant like as steam lines, gas lines and liquid hydrocarbon lines.

nevermind

You wrote that someone told you,

" I have always been told that it had to be at least 1/2 the diameter of the header or less."

This is "BOGUS", Wrong, etc. There is no such thing in the Code or in actual practice by the industry.

Very nice chart, Abdel. It will hang in my office for years (or perhaps only weeks, as the company appears to be circling the drain).