Impedance heating of pipelines and equipment - Application guide for design, installation, testing, commissioning, and maintenance

1.1 General

This standard is divided into seven clauses. Clause 1 provides the scope and purpose. Clause 2 lists references to other standards that are useful in applying this standard. Clause 3 references definitions that are found in IEEE Std 844.3/CSA C22.2 No.293.3. Clause 4 establishes the design guidelines for impedance heating. Clause 5 provides installation considerations and guidelines. Clause 6 covers field testing, start-up, commissioning, and operation of impedance heating systems. Clause 7 provides maintenance and repair guidelines.

This standard also contains annexes. Annex A provides bibliographical references. Annex B provides pipe heat loss calculation methods. Annex C provides heat-up and cool-down calculation methods. Annex D provides a method to determine equivalent thicknesses of insulating cements. Annex E provides an example of design input parameters for an impedance heating design. Annex F presents an example of a record for installation requirements. Annex G shows an example of a form that can be used to document the commissioning of the system. Annex H presents an example of a preventive maintenance record. Annex I shows the insulated impedance conductor types covered in this standard.

1.2 Scope

This standard provides for the application of impedance heating systems for steel or steel alloy pipe and equipment. It provides recommendations for design, installation, maintenance, and repair of these systems in general industry applications.

This standard applies to impedance heating systems intended to be installed in ordinary and hazardous locations with explosive atmospheres. The hazardous locations include the following:

- In Canada: Zone 2; Zone 22; or Class I, Division 2; Class II, Division 2; Class III, Division 2 as described in CSA C22.1; and 
- In the USA: Class I, Zone 2; Zone 22; or Class I, Division 2; Class II, Division 2; Class III, Division 2 as described in the NEC.

This standard, when used with other recognized codes and standards, is intended to cover impedance heating systems in their entirety, including system design, specification, installation, operation, testing, commissioning, and maintenance. This document also addresses the following associated systems that are important to the performance of impedance heating systems:

a) Thermal insulation systems;
b) Electric power supply systems;
c) Electric grounding systems; and
d) Control and monitoring systems.

1.3 Purpose

This standard is intended to aid the user in specifying, installing, operating, testing during commissioning, and maintaining impedance heating systems that:

a) Maintain design temperature; 
b) Provide electrical, thermal, and mechanical durability and reliability; and
c) Reduce hazards to the user and the surroundings.

Design information, selection parameters, and data in this standard are not intended to provide a complete design primer for impedance heating systems. The information presented provides guidelines for the following:

- Selecting the optimum impedance heating system design;
- Establishing design criteria and constraints for the heated pipeline or equipment to help ensure system compatibility;
- Preparing specifications to obtain quotations for impedance heating systems; and
- Developing information on installation, operation, testing, commissioning, and maintenance of the impedance heating system.

1.4 Terminology

In this standard, shall is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; should is used to express a recommendation or that which is advised but not required; and may is used to express an option or that which is permissible within the limits of the standard.

Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.

Notes to tables and figures are considered part of the table or figure and may be written as requirements.

Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.