It has become widely recognized that the selection and design of pipe hangers is an important part of the engineering study of any modern steam generating or process installation. Problems of pipe design for high temperature, high pressure installations have become critical to a point where it is imperative that such aspects of design as the effect of concentrated hanger loads on building structure, pipe weight loads on equipment connections, and physical clearances of the hanger components with piping and structure be taken into account at the early design stages of a project.

Problems presented in the design of hangers for nuclear power plants may vary substantially from those in fossil fuel generating plants. Temperatures are more moderate but the nature of nuclear energy demands fail safe hanger design as dictated by the Nuclear Regulatory Commission and in compliance with pertinent codes.

Engineers specializing in the design of pipe hangers have established efficient methods of performing the work required to arrive at appropriate hanger designs. However, the engineer who devotes varying portions of his time to the design of pipe hangers often must gather a considerable amount of reference data peculiar only to the hanger calculations for his current project.

It is the purpose of this article to present a compilation of all information necessary for the design of hangers, including a technical section devoted to the listing of piping material, weights, and thermal expansion data. Also, the discussions of the various steps involved in designing supports, presented here in their proper sequence, should serve as a good reference source for the engineer who only occasionally becomes involved in the essentials of hanger design.

The first of these steps is that of determining and obtaining the necessary amount of basic information before proceeding with calculations and detailing of the pipe supports. No design is complete unless the engineer has had the opportunity to review the equivalent of the following project data:

• complete set of piping drawings.

• complete set of steel and structural drawings including equipment foundation and structure details.

• A complete set of drawings showing the location of ventilating ducts, electrical trays, pumps, tanks, etc.

• The appropriate piping specifications and data, which will include pipe sizes and composition identification, wall thicknesses, and operating temperatures.

• A copy of the insulation specifications with densities.

• Valve and special fittings lists, which will indicate weights.

• The movements of all critical equipment connections such as boiler headers, steam drums, turbine connections, etc.

• The results of the stress, flexibility and movement calculation performed for critical systems.

• The steps in which the engineer will apply this basic information are as follows:

(1) The determination of hanger locations.

(2) The determination of the thermal movement of the piping at each hanger location.

(3) The calculation of hanger loads.

(4) 'The selection of hanger types, i.e., spring assembly, either of the constant support or variable spring type, rigid assembly, etc.

(5) The checking of clearance between the hanger components and nearby piping, electrical cable trays, conduits, ventilating ducts, and equipment.

The final step will not be discussed to any great degree. Obviously, this aspect of design is governed solely by the requirements and layouts of the individual job. Instead, attention will be devoted to steps I through 4, where the scope of good hanger practice can be generally defined for any installation.