Best to check with your local inspector to establish what the approved materials in your area are.
However in saying that I would strongly advise you to obtain the services of a suitably qualified gasfitter to undertake all the gasfitting work for you.
Gas can and has proved to be dangerous in the hands of the experienced – safety is paramount in our business and so it should be in your life!!!!!!!!!!
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians