TWI runs the British Gas Approved Scheme (BGAS) formerly referred to as 'ERS', on behalf of NATIONAL GRID Plc (

Although it is recommended that candidates receive training, there are no specific training and experience requirements for any of the qualifications.

The system is primarily designed for inspectors involved in one or more of a number of activities related to pipelines. BGAS-CSWIP qualifications are highly regarded pipeline specific qualifications, which complement the well-known CSWIP inspection qualifications, both are internationally recognised.

The following categories of certification are available from TWI:

UK only:
  • Senior Pipeline Inspector
  • Senior Inspector (Welding)
  • Ultrasonic Operator
  • Ultrasonic Operator (Plate)
  • Magnetic Particle Inspector
  • Site Coating Inspector

  • Welding Inspector
  • Radiographer
  • Radiographic Assistant
  • Painting Inspector
  • Agricultural and Environmental Inspector
  • Mill Coating Inspector
  • Blast Cleaning/Preparation Operative
  • Painting Operative
  • Painting Supervisor

For all subjects, exam duration is from half to a full day depending on categories of examination sought.


A number of narrative answer and/or multiple choice questions - no time limit specified.

Practical exams (applicable for most categories of examination)

Demonstration of practical abilities in the performance of a number of finite practical tasks.


The examinations contain an oral assessment.

Falsification of BGAS certificates:

TWI Examination Ltd reminds all employers that a certificate verification is offered free of charge - please take advantage of this before you employ anyone claiming to hold a BGAS-CSWIP certificate.

Equally, legitimate certificate holders should always ensure that their own certificate is in a safe place and not accessible to opportunists who try to falsify certificates.

Anyone discovered falsifying a certificate is immediately reported to the police.

Simply contact us with the name and certificate number for verification and be sure you are employing a legitimate holder.