This specification defines the minimum mandatory requirements governing material, mechanical design, fabrication, erection, inspection, and testing of low-pressure storage tanks. 1.1.2 This specification does not cover tanks designed in accordance with Appendix Q "Low-Pressure Storage Tanks for Liquefied Hydrocarbons Gases" and double wall tanks according to Appendix R "Low-Pressure Storage Tanks for Refrigerated Products" of API STD 620. Additional requirements for such tanks shall be developed, if necessary, by the Design Engineer. Such requirements shall be submitted to the Company’s Engineer prior to bidding with sufficient time for review. 1.1.3 This specification shall be attached to and form an integral part of a purchase order. 1.1.4 Conflicts and Deviations 1.1.4.1 Any conflicts between this specification and other Company’s Materials System Specifications (CMSSs), Company’s Engineering Standards (CESs), Industry codes and standards, and Company’s Standard Drawings (CSDs) and Forms shall be resolved in writing by the Company or Buyer Representative. 1.1.4.2 Direct all requests to deviate from this specification in writing to the Company or Buyer Representative. 1.2 Coverage 1.2.5 (Exception) Horizontal cylindrical tanks used for the storage of hydrocarbon liquids within the scope of API STD 620, with design pressures in their gas or vapor spaces not more than 103 kPa gauge (15 psig).