4.5　Boiler Sealing Elements

4.5.1　The water seal gland trough body shall be erected flatly.The inserting plate and the equipment shall be connected firmly，and all welds shall be tight without leakage.The expansion of the inserting plate shall be free at the hot state.After the erection of the water seal gland trough and before sealing，the expansion clearance shall be recorded and the trough shall be cleaned completely.

4.5.2　The welds in the wave form expansion joints shall be leakfree.The wave band shall be fine.During erection，the cold drawing value or compression value shall meet the drawing requirements and they shall be recorded，and the welds in the internal protection iron plates shall be in the medium inlet side.

4.5.3　The joining surface of sealing devices fixed with bolts and the erection/tightening requirements for the bolts shall comply with the requirements of Article 4.5.2 in this Part.

4.5.4　The elliptic bolt hole positions in steam drum/header shell and the sealing iron plate joints must be adjusted correctly so that the expansion of steam drum and headers shall not be constrained.

4.5.5　The seal elements welded in the heating surface shall be erected and welded prior to hydrostatic test of the heating surface，and there shall be leakfree in the welds.

4.5.6　The furnace top large cover cladding frame shall be welded in the furnace top hanging device or the pre-buried parts to the pressure components，and enough expansion clearance shall be reserved according to the manufacturer's drawing requirements.The erection of outer casings shall be carried out with firm overlapping and the direction of overlapping shall be consistent.The location for the hanging device perforating the large cover shall be equipped with the sealing devices.The furnace top large cover for personnel accessing shall be equipped with the safety fences.

4.5.7　The locations for the pipe/hanger frame perforating the large cover shall be provided with enough expansion clearance and they shall be equipped with the flexible seals.

4.5.8　The ducts in the ventilation beams shall be smooth.The welds shall be tight without leakage，and the expansion clearance shall be reserved according to the manufacturer's drawing requirements during erection.

4.5.9　The cold drawing/compression value of any compensator shall meet the drawing requirements and it shall be recorded.The erection directions of the drain ports of the nonmetal compensators shall be correct.The dampers inside the compensators shall be arranged along the flow direction，and the nonmetallic compensators shall be packed tightly and densely with the insulation materials after the erection of non-metal compensators.