Good Practice of inspecting Flange joints prior to Bolting

Flange surfaces shall be finished in accordance with the flange finish description referred to by the Piping Class. Gasket surfaces shall be inspected by the fit up crew, and shall not show evidence of damage, or Contaminants. The bolt or nut seating surface shall be flat and provide a low friction, full contact area for Bolt head or nut. Discrepancies shall be addressed to Field Engineering for evaluation. Note: Cast firewater Valves / flanges are an exception to this rule. In extreme case, the flange may require re-machining.

1. Gasket surface areas shall be cleaned in accordance with the gasket manufacturer’s installation instructions. Typically previous gasket materials and contaminants such as dirt, oil, and grease. Thin, uniform preservative coatings are generally acceptable. Provided they do not fill seating finish or show evidence of build up or runs. When using a wire brush for cleaning, ensure the wire brush is compatible with the flange material i.e. do not use carbon steel bristles on stainless steel flanges. The direction of

brushing shall also follow the seating surface grooves or finish. Take care not to over smooth the finish, and use only Hand brushes. Depending on gasket type, minimum profiles are required for optimum gasket performance. Power brushes shall only be used, if approved by Field Engineering.

2. Flange gasket seating surfaces shall be inspected for scratches, dents, scoring, and other damage. Depending on the gasket type, pipe size, and extent of imperfections, some deviation can be accommodated, without flanged joint degradation. Contact Field Engineering if further interpretation is required.

3. Flange seating surfaces shall also be monitored for flatness, around their circumference