This Publication relates to "in-service" situations, such as testing after major modification, significant repair or re-rating, rather than new build. It has been developed to assist owners and operators of pressure equipment to determine where it may be permissible to waive a hydrostatic pressure test before re-introducing equipment into service and instead rely on other forms of integrity assurance.

As explained in the previous Section, new equipment may or may not be hydrostatically tested. The focus of this Guide is on vessels, pipework and other components which may be found in pressure systems and which would traditionally be hydrostatically tested during new build and where today, in service, a pressure test waiver may be justified.

The Guide does not at this stage major on the in-service considerations of plant and equipment where safety assurance during new build is developed by techniques other than hydrostatic testing. However, it is envisaged that such guidance could form part of a future edition of this publication.

The contents of this Guide are primarily relevant to systems and pressure equipment covered by the UK Pressure Systems Safety Regulations (PSSR), but are also applicable to other pressure equipment normally subject to pressure testing to safeguard against loss of containment. This Publication does not cover the special case of atmospheric storage tanks; users are referred instead to the guidance in EEMUA Publication 159.

The key aspects of pressure testing existing (in-service rather than new) pressure equipment are discussed. The relative advantages of pressure testing and nondestructive examination are described. A specimen form is provided to formalise an assessment of the need to pressure test and to record, where applicable, the justification for waiving one.

This publication has been prepared by the Engineering Equipment and Materials Users? Association, in consultation with the GB Health and Safety Executive.