PREFACE This chapter is one of a series which make- up the manual@ Guide for Inspection of Refinery Equipment. It has been- formulated by the joint effort of the Subcommittee of Refinery Inspection Supervisors and the Designers' Subcommittee on Refinery Inspections@ and has been reviewed and approved by the Committee on Refinery Equipment. The information contained in this publication has been arranged in its present form as a means of facilitating continuity of presentation and convenience of reference. It does not constitute@ and should not be construed to be@ a code of rules@ regulations@ or minimum safe practices. It is not intended that the practices described in this publication supplant practices that have been proven satisfactory. Nor. is it intended that this publication discourage innovation and originality in the inspection of refineries. Users of the publication are reminded that no book or manual is a substitute for the judgment of a responsible engineer.