Design header in steam boiler should comply to ASME Boiler & Pressure Vessel Section I (ASME BPV). Header shells can be manufactured by a seamless process. Feed water connections to drums should be of a thermal sleeve design unless an alternative design is agreed with the owner.
Headers should be provided with access arrangements to allow full internal visual inspection and cleaning. Wherever possible, the access openings should be through header ends and should be arranged in order that the numbers of inspection openings are minimized. The openings shall have an internal diameter of at least 75mm in order to allow televisual inspection of the complete header.
The closure of these openings should be of a permanent type, fixed by means of fully penetrating butt welds with suitable length allowance for future cutting and re-welding.
All headers which are designed on a time dependent basis should be fitted with creep pips or other means, to allow periodic measurement of diametric creep distension.
All nozzles, branches and tube stubs should be attached by welding and should be of the set on type. The weld preparations and welding procedures should ensure fully penetrating welds. Reinforcing pads should not be used.
No nozzle, branch or tube stub weld shall encroach over the heat affected zone of main seam welds. Any specific instances where these requirements cannot be complied with should be submitted to the Purchaser for approval during the design phase.
All nozzles, branches and tube stubs shall be of a sufficient length to ensure adequate access for welding on the adjoining tubes or pipes and to permit effective post weld heat treatment of these butt welds so as not to affect the integrity of the drum / headers.
Design header in steam boiler should be performed to ensure safety during operation. Diameter, thickness and material to be used should be calculated as per design