Design, installation and maintenance of medical, dental, laboratory and industrial gas pipework, plant and equipment. HPI engineers are also fully certified in Orbital, TIG and Brazed Welding. BS EN 9606 With all our engineers having personal qualifications via either a Mechanical or Electrical apprenticeship ( City & Guilds or equivalent ) background allowing them to be certified as Competent Persons for Medical Gas installation as per both the HTM 02-01, SHTM 02-01 requirements.