Gaskets are mechanical seals, usually formed like a ring and used for sealing of flange joints.
Various types of gaskets are available depending upon their construction, materials, and features.The following are the type of gaskets commonly used: Non-Metallic Gaskets (ASME B 16.21) Spiral-Wound Gaskets (ASME B 16.20) Ring Joint Gaskets (ASME B 16.20) Non-Metallic Gaskets are used with flat face or raised face flanges. Spiral-Wound Gaskets are used with raised face flanges. They are available with an inner ring and outer ring, which is also known as the cantering ring. Ring Joint Gaskets are used with Ring Type Joint (RTJ) flanges.
They are available in octagonal or oval cross sections. A very high surface stress is developed between an RTJ gasket and the flange groove when RTJ is bolted up in a flange.
This leads to plastic deformation of the gasket.
A plumber is a tradesperson who specializes in installing and maintaining systems used for potable (drinking) water, sewage and drainage in plumbing systems.
Much of the plumbing work in populated areas is regulated by government or quasi-government agencies due to the direct impact on the public's health, safety, and welfare.
If permits are required for work, plumbing contractors typically secure them from the authorities on behalf of home or building owners. In the United Kingdom the professional body is the Chartered Institute of Plumbing and Heating Engineering (educational charity status) and it is true that the trade still remains virtually ungoverned; there are no systems in place to monitor or control the activities of unqualified plumbers or those home owners who choose to undertake installation and maintenance works themselves, despite the health and safety issues which arise from such works when they are undertaken incorrectly; see Health Aspects of Plumbing (HAP) published jointly by the World Health Organization (WHO) and the World Plumbing Council (WPC).WPC has subsequently appointed a representative to the World Health Organization to take forward various projects related to Health Aspects of Plumbing.Źródło: https://en.wikipedia.org/wiki/Plumbing.