ABSTRACT

Thermal fluid heat transfer systems require attention to many design details. These details may often seem less important when compared to issues dealing with the processing portion of new facilities. However, items overlooked in the design of the heat transfer system can often cause delays to important project start up schedules. The use of checklists during the design phase of a project can help to prevent these types of delays as well as ensure the system performs as expected. A design checklist should consider general aspects of the system such as pressure/temperature ratings of equipment, fluid flow measurement, electrical area classifications,-piping cleanout and preparation, and safety-related matters. In addition, specific sections covering fluid heaters or waste heat units, pumps, piping and vessel design, flange and valve specifications and procedures, gaskets and packing, and thermal insulation and covering should also be included. A prestart-up checklist should be assembled as well, to provide not only a final verification of many of the above topics, but to outline items which a start-up engineer can reasonably be expected to check and/or correct in the field.

INTRODUCTION

Heat transfer systems utilizing high temperature, synthetic fluids are an essential part of virtually all chemical processing plants. And, while the fundamental concepts of heat flow are well known, the system designer often finds that there are many ways to implement these concepts--so many that the design of a system may appear to present an enormously complex task. To aid the system designer in this effort, Dow Corning has drawn on its experience in the liquid-phase heat transfer area and compiled a general guideline.(or checklist) for basic system design. The topics covered are of a general nature because it would not be possible to cover all of the alternatives involved in individual heat transfer applications. And, of course, the information presented should be considered as only being supplemental to those recommendations supplied by equipment and materials manufacturers.

HEAT TRANSFER SYSTEM DESIGN CHECKLIST
1.0 GENERAL

  1. Pressure/temperature ratings of equipment are in accordance with design temperature requirements.

  2. Proper electrical classifications for system components and vapor discharge areas have been determined.

  3. System and surrounding facilities protected from fire exposure by automatic sprinklers (with a recommended density of 0.25 gpm/square foot and a 3000 square foot minimum), insulated structural Steel members and the installation of alarm systems and portable fire extinguishing equipment (low-expansion, aqueous film-forming foams (AFFF) are recommended).

  4. Provisions completed for unloading and storage (if applicable) of heat transfer fluid, e.g. drums should be covered or stored inside to prevent possible fluid contamination from standing water on top of drum.

  5. Clean-out procedures have been developed that will ensure a clean system with a minimum amount of residual moisture.

  6. Procedures developed for final pressure testing of system.

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