Head Covers Sample Clauses

Head Covers. (a) The covers shall be of cast stainless steel and sufficiently rigid so that deflections under service condition have no adverse effect on the performance of the turbine. (b) The covers shall be fitted with fixed stainless-steel seals for the runner and stainless-steel liners for the stay vanes; these seals and liners shall be replaceable. The stainless steel used shall be to a weldable grade. The Contractor shall demonstrate by representative tests that the composition of the liners is such that in the event of contact between the stay vanes and liners or rotating and fixed seals that galling or pick-up will not occur. (c) Means shall be provided for checking the clearance between the fixed and rotating portions of all runner seals in at least four equally spaced points around each seal diameter, with a minimum of dismantling. (d) Any portion of the cover subject to water flow shall be overlaid with stainless steel. A stainless-steel liner shall be provided in the bottom cover/draft tube bend which shall extend downstream from the runner outlet. (e) No joint rings or gaskets which cannot be renewed after completion of the installation shall be incorporated. (f) A system shall be provided for correcting any deviation in hydraulic thrust from the designed value including deviation due to wear in the runner seals.