A heat pipe includes a hollow body having a fluid filling end which is covered with an elastic sealing member. The sealing member is pierced with a needle by extending the needle through the sealing member and into the hollow body. Air is drawn out from within the hollow body through the needle and a heat transfer fluid is introduced into the hollow body through the needle. The sealing member provides a passage for the needle when the sealing member is pierced and contracts to seal the passage after the needle is removed from the sealing member.