A clamp for a pipe, comprising: - a first clamp section comprising a rigid body, extending along a portion of a circle for bearing on a first portion of the periphery of a pipe, said first clamp section comprising a first end and a second end, - a second clamp section, comprising a rigid body, extending along a portion of a circle for bearing on a second portion of the periphery of said pipe, diametrically opposite to said first portion, said second clamp section comprising a first end and a second end, - hinging means connecting the first end of the first clamp section and the first end of the second clamp section comprising a hinge pin pivotably mounted in at least one opening, said hinge pin being integral with the first end of the first clamp section and said at least one opening integral with the first end of the second clamp section, or reversely said hinge pin being integral with the first end of the second clamp section and said at least one opening integral with the first end of the first clamp section, - connecting and clamping means, removably configured so as to enable transition from a stowed position to a connecting position connecting the second end of the first clamp section to the second end of the second clamp section to ensure clamping of the clamp to the pipe, said stowed position ensuring the opening of the clamp by spacing apart the first clamp section from the second clamp section in connection with said hinging means, and then removably inserting a pipe through a clearance of the clamp left by stowing said removable connecting means, and spacing apart the first clamp section from the second clamp section by pivoting the hinging means, and wherein the clamp comprises a diameter adjustment system configured to allow change in diameter of the clamp, without separating the first clamp section from the second clamp section still connected through said hinging means, said adjustment system comprising said hinge pin which comprises at least one lug (40, 41) with a non-circular section, said at least one opening comprising a pair of adjustment openings (43, 44) allowing two distinct adjustment positions for the hinge pin of which said lug (40; 41) with a non-circular section is held captive in either or the two adjustment openings (43, 44) in a closing position of the clamp, and wherein a throat, with a width less than the diameter of the adjustment openings (43, 44) communicates the two openings of the pair of adjustment openings (43, 44) with each other, by allowing upon opening the clamp by pivoting said hinge pin (40, 41) relative to either of the two adjustment openings; pivoting said lug with a non-circular section to a position allowing engagement of said lug with a non-circular section through the throat, and thus the change in position of the hinge pin from one to the other of the two openings of the pair of adjustment openings (43,44) by sliding said at least one lug (40, 41) with a non-circular section through the throat. - a first clamp section comprising a rigid body, extending along a portion of a circle for bearing on a first portion of the periphery of a pipe, said first clamp section comprising a first end and a second end, - a second clamp section, comprising a rigid body, extending along a portion of a circle for bearing on a second portion of the periphery of said pipe, diametrically opposite to said first portion, said second clamp section comprising a first end and a second end, - hinging means connecting the first end of the first clamp section and the first end of the second clamp section comprising a hinge pin pivotably mounted in at least one opening, said hinge pin being integral with the first end of the first clamp section and said at least one opening integral with the first end of the second clamp section, or reversely said hinge pin being integral with the first end of the second clamp section and said at least one opening integral with the first end of the first clamp section, - connecting and clamping means, removably configured so as to enable transition from a stowed position to a connecting position connecting the second end of the first clamp section to the second end of the second clamp section to ensure clamping of the clamp to the pipe, said stowed position ensuring the opening of the clamp by spacing apart the first clamp section from the second clamp section in connection with said hinging means, and then removably inserting a pipe through a clearance of the clamp left by stowing said removable connecting means, and spacing apart the first clamp section from the second clamp section by pivoting the hinging means,