ISO 16528-1:2007 defines the performance requirements for the construction of boilers and pressure vessels. It is not the intent of ISO 16528-1:2007 to address operation, maintenance and in-service inspection of boilers and pressure vessels. In relation to the geometry of the pressure-containing parts for pressure vessels, ISO 16528-1:2007 includes welding end connection for the first circumferential joint for welded connections, first threaded joint for screwed connections, face of the first flange for bolted, flanged connections, first sealing surface for proprietary connections or fittings and safety accessories, where necessary. In relation to the geometry of pressure-containing parts for boilers, ISO 16528-1:2007 covers feedwater inlet (including the inlet valve) to steam outlet (including the outlet valve), including all inter-connecting tubing that can be exposed to a risk of overheating and cannot be isolated from the main system, associated safety accessories and connections to the boilers involved in services such as draining, venting, desuperheating, etc. ISO 16528-1:2007 does not apply for nuclear components, railway and marine boilers, gas cylinders or piping systems or mechanical equipment, e.g. turbine and machinery casings.