Valve cover for a reciprocating internal combustion engine, in which an oil separation device (64, 66, 68, 70) for separating oil droplets from blow-by gases of the internal combustion engine is integrated, and which forms a chamber (A, B) through which the blow-by gas can flow, the chamber having a gas inlet and a gas outlet, and the separation device being arranged in the chamber, wherein (a) at least one impact wall (66, 68, 70), against which the flow of gas can flow transversely, for separating oil droplets from the flow of gas and/or for diverting separated oil from the flow of gas, projects into the chamber, (b) the valve cover comprises two outer parts, namely an essentially hood-like upper part and an essentially dish-like lower part, and also an essentially plate-like intermediate part arranged between the outer parts, (c) the upper part and the intermediate part together form the chamber (A, B), and the intermediate part forms a chamber bottom, which is closed at least in the area of the separation device except for at least one oil outlet opening (34, 36), (d) at least one oil collection pan (30, 32) for separated oil, having a pan bottom, is formed in the lower part, the oil collection pan being covered by the intermediate part and communicating with the chamber (A, B) via the oil outlet opening (34, 36), (e) the outer parts (10, 14) lie against each other with joining surfaces (54, 56), each formed by a wall area of the two outer parts, (f) the intermediate part rests on a first of the two outer parts (10, 14) and at its circumferential edge area abuts with a first joining surface facing the second outer part on a second joining surface of the second outer part, a third joining surface provided on the first outer part and facing the second outer part abuts on a fourth joining surface of the second outer part, and, in a plan view of the valve cover, the third and the fourth joining surfaces enclose the first and the second joining surfaces (50 and 52, respectively), (g) the two outer parts (10, 14) and the intermediate part are thermoplastic parts, (h) wall areas of the two outer parts (10, 14) covering the second, the third and the fourth joining surface consist of a material which is at least substantially impermeable to welding laser light, (i) the two outer parts (10, 14) and the intermediate part are joined to one another in the four joining surfaces (50, 52, 54, 56) by hot gas-weld seams, and (j) all of the weld seams lie exclusively in the joining surfaces (50, 52, 54, 56). (a) at least one impact wall (66, 68, 70), against which the flow of gas can flow transversely, for separating oil droplets from the flow of gas and/or for diverting separated oil from the flow of gas, projects into the chamber, (b) the valve cover comprises two outer parts, namely an essentially hood-like upper part and an essentially dish-like lower part, and also an essentially plate-like intermediate part arranged between the outer parts, (c) the upper part and the intermediate part together form the chamber (A, B), and the intermediate part forms a chamber bottom, which is closed at least in the area of the separation device except for at least one oil outlet opening (34, 36), (d) at least one oil collection pan (30, 32) for separated oil, having a pan bottom, is formed in the lower part, the oil collection pan being covered by the intermediate part and communicating with the chamber (A, B) via the oil outlet opening (34, 36), (e) the outer parts (10, 14) lie against each other with joining surfaces (54, 56), each formed by a wall area of the two outer parts, (f) the intermediate part rests on a first of the two outer parts (10, 14) and at its circumferential edge area abuts with a first joining surface facing the second outer part on a second joining surface of the second outer part, a third joining surface provided on the first outer part and facing the second outer part abuts on a fourth joining surface of the second outer part, and, in a plan view of the valve cover, the third and the fourth joining surfaces enclose the first and the second joining surfaces (50 and 52, respectively), (g) the two outer parts (10, 14) and the intermediate part are thermoplastic parts, (h) wall areas of the two outer parts (10, 14) covering the second, the third and the fourth joining surface consist of a material which is at least substantially impermeable to welding laser light, (i) the two outer parts (10, 14) and the intermediate part are joined to one another in the four joining surfaces (50, 52, 54, 56) by hot gas-weld seams, and (j) all of the weld seams lie exclusively in the joining surfaces (50, 52, 54, 56).