Abstract: A nipple for a coaxial coupling is disclosed. The nipple comprises a housing (40), and a nipple tube (30) arranged in the housing (40). The nipple comprises a first passage (42) between the housing (40) and the nipple tube (30), and the nipple tube (30) comprising a second passage (32) within the nipple tube (30). A relief valve (20) is slideably arranged in the nipple tube (30). The nipple comprises sealing means (24, 26) for sealing between the nipple tube (30) and the relief valve (20). The nipple tube (30) further comprises a relief passage (34), the relief passage (34) forming a fluid passage between the first passage (42) and the second passage (32). The relief passage (34) being arranged so that the sealing means (24, 26) seals the relief passage (34) when the nipple is fully coupled.