For the purpose of the standard following definitions apply-API 510 Pressure Vessel inspection code

1. Alteration: A physical change in any component or rerating that has design implications that affect the pressure containing capability of a pressure vessel beyond the scope of the items described in existing data reports. The following should not be considered alterations:

–                      Any comparable or duplicate replacement, the addition of any reinforced nozzle less than or equal to the size of existing reinforced nozzles, and the addition of nozzles not requiring reinforcement.

1. Authorized Pressure vessel inspector: An employee of an authorized inspection agency who is qualified and certified to perform inspection under this inspection code.
2. Authorized inspection agency: Any one of the following
   1. The inspection organization of the jurisdiction in which the pressure vessel is used
   2. The inspection organization of insurance company that is licensed or registered to write and actually does write the pressure vessel insurance.
      1. The inspection organization of an owner or user of pressure vessels who maintains an inspection organization for his equipment only and not for vessel intended for sale or re-sale.
      2. An independent organization or individual i.e. under contract to and under the direction of an owner-user and that is recognized or otherwise not prohibited by the jurisdiction in which the pressure vessel is used. The owner-user’s inspection program shall provide the controls that are necessary when contract inspectors are used.

Maximum allowable working pressure: Maximum gauge pressure permitted at the top of the pressure vessel in its operating position for a designated temperature. This pressure is based on calculation using the minimum (or average pitted) thickness for all critical vessel elements, exclusive of thickness designed for corrosion and loadings other than 

1. pressure.
2. On stream inspection: The inspection used to establish the suitability of pressure vessel continued operation. Non destructive examination (NDE) procedures are used to establish the suitability of the vessel, and the vessel may or may not be in operation while the inspection is being carried out. Because a vessel may be in operation while an on-stream inspection is being carried out, and on-stream inspection means essentially that the vessel is not entered for internal inspection.
3. Repair organization: Any one of the following
   1. The holder of a valid ASME Certificate of authorization that authorizes the use of an appropriate ASME Code symbol stamp.
   2. An owner or user of pressure vessels who repairs his or her own equipment in accordance with this inspection code.
   3. A contractor whose qualifications are acceptable to the pressure vessel owner or user and who makes repairs in accordance with this inspection code.
   4. An individual or organization that is authorized by the legal jurisdiction.
4. Rerating: A change in either the temperature rating or maximum allowable working pressure rating of a vessel, or a change in both, the maximum allowable working temperature and pressure of a vessel may be increased or decreased because of rating, and sometimes a rerating require a combination of changes. Derating below original design conditions is a permissible way to provide for corrosion. When a rerating is conducted in which the maximum allowable working pressure or temperature is increased or the minimum temperature is decreased so that additional mechanical tests are required, it shall be considered alterations. API 510 pressure vessel inspection code