A vacuum system pipe coupling comprising a first coupling member defining a through passage, a second coupling member defining a through passage and a securing unit, wherein the first and second coupling members (36,38) are made of metal, wherein said first coupling member has a first end portion having a first lengthways extending axis, a second end portion having a second lengthways extending axis that is laterally offset with respect to said first lengthways extending axis and a first connecting portion connecting said first end portion with said second end portion, wherein said second coupling member has a third end portion having a third lengthways extending axis, a fourth end portion having a fourth lengthways extending axis that is laterally offset with respect to said third lengthways extending axis and a second connecting portion connecting said third end portion with said fourth end portion, wherein said securing unit is configured to secure said first end portion to said third end portion with said first and third lengthways extending axes (44, 54) in alignment, wherein said first and second coupling members (36, 38) comprise respective pipe members, and wherein the pipe member of the first coupling member at least partially defines said first and second end portions (42,46) and said first connecting portion and the pipe member of the second coupling member at least partially defines said third and fourth end portions (52,56) and said second connecting portion, the vacuum system pipe coupling further comprising a pipe heater, wherein said pipe heater has an inner face and, in use, is wrapped about said pipe member of said first coupling member such that said inner face engages said pipe member and in at least one of a lengthways and a widthways direction of said inner face there is no discontinuity in the engagement between the inner face and first coupling member. wherein said first coupling member has a first end portion having a first lengthways extending axis, a second end portion having a second lengthways extending axis that is laterally offset with respect to said first lengthways extending axis and a first connecting portion connecting said first end portion with said second end portion, wherein said second coupling member has a third end portion having a third lengthways extending axis, a fourth end portion having a fourth lengthways extending axis that is laterally offset with respect to said third lengthways extending axis and a second connecting portion connecting said third end portion with said fourth end portion, wherein said securing unit is configured to secure said first end portion to said third end portion with said first and third lengthways extending axes (44, 54) in alignment, wherein said first and second coupling members (36, 38) comprise respective pipe members, and wherein the pipe member of the first coupling member at least partially defines said first and second end portions (42,46) and said first connecting portion and the pipe member of the second coupling member at least partially defines said third and fourth end portions (52,56) and said second connecting portion, the vacuum system pipe coupling further comprising a pipe heater, wherein said pipe heater has an inner face and, in use, is wrapped about said pipe member of said first coupling member such that said inner face engages said pipe member and in at least one of a lengthways and a widthways direction of said inner face there is no discontinuity in the engagement between the inner face and first coupling member.