All gas engineers should be registered on the Gas Safe® Register for each equipment in which they're competent to undertake work on. http://tmpccc.com/index.php?language=vi&nv=news&nvvithemever=t&nv_redirect=aHR0cHM6Ly9DYW52YXMuaW5zdHJ1Y3R1cmUuY29tL2Vwb3J0Zm9saW9zLzMyMTUxMTQvSG9tZS9fRG9faXRfeW91cnNlbGZfdnNfRXhwZXJ0X0NlbnRyYWxfaGVhdGluZ19ib2lsZXJfU2V0dXBfV2hhdF9Zb3VfUmVxdWlyZWRfdG9fS25vdw