This International Standard specifies the equipment and procedures for determining the short-term water absorption of preformed pipe insulation by partial immersion in water. It is applicable to thermal insulating products. NOTE It is intended to simulate the water absorption caused by exposure to rain for 24 h during product installation. If the pipe insulation is cut from a flat product, then the short-term water absorption by partial immersion can be obtained from tests carried out on the flat product with similar properties in accordance with ISO 29767, provided that the test is carried out in the direction giving the highest water uptake. This International Standard has been prepared for products used to insulate building equipment and industrial installations, but it may also be applied to products used in other areas. No existing International Standards supersede this one.