Shop assembled, steam drum, risers, downcomers, and all other related equipment on the steam side shall be designed, fabricated and hydrostatically tested to all requirements of ASME Section I, Power boilers, henceforth will be known as the Code.
The seller shall also submit for the purchaser's acceptance, mechanical calculations of the WHB system, including exchanger and steam drum support calculations, platform structural calculations, wind and seismic loading to NBC of Canada and finite element analysis.
Corrosion allowances for tubes shall be 1.0 mm (1/32"). Channels and tubesheet corrosion allowances shall be 3.2 mm (1/8") for the process side and 1.6 mm (1/16") for the water side of shell.
External insulation shall not be applied on inlet channel. Unless otherwise stated in the data sheet, insulation on intermediate and outlet channels, on the shell portion of the exchanger, the steam drum, the risers and downcomers shall be provided by others.
The design metal temperature of channels, shell, tubes and tubesheet shall be restricted to 343oC (650oF). However, if tube metal temperature exceeds 343oC (650oF) it shall not be greater than 399oC (750oF). All connections shall be flanged, except risers, downcomers and the combustion chamber connections, which shall be beveled for full penetration welds.
Minimum nozzle size shall be 2" NPS with RFWN rated flanges. Nozzles shall not be located 50 mm (2") of any weld seams. Internal connections when flanged, shall be bolted with non-asbestos type gaskets; i.e., clinger C4400 and using bolting materials - SA 193 B8/304 CL1, 1A and SA 194-8.
The fabricator shall provide operating manuals, which shall be divided into at least four sections:
i. start-up
ii. operation
iii. shutdown and
iv. maintenance and spare parts
Before start-up, the manual shall provide instruction for acid cleaning of inside walls of drum and tubes from dirt and scales by using inhibited acid, passivation by alkaline wash and subsequently clean water flushing. Instruction shall be clear as to the strength of acid and alkaline solutions and quality of flushing water to be used. Furthermore, the manual shall advise whether removal of drum internals during acid cleaning operation is necessary.