This standard specifies the type, opening method, dimension, manufacturing tolerance and of the welding tube holes on pressure parts of industrial boilers.
This standard is applicable to the stationary steel steam boilers of which the rated working pressure is greater than 0.04MPa but less than 3.8MPa, the rated steam output is not less than 0.1t/h and the medium is water as well as the stationary steel hot water boilers of which the rated water-delivery pressure is greater than 0.1MPa.
2 Normative References
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments to (excluding amending error in the text), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the normative document applies.
GB/T 1804-1992 "General Tolerances-Tolerances for Linear and Angular Dimensions without Individual Tolerance Indications"
3 Type of Tube Holes and Method for Opening Holes
3.1 The type of welding tube holes on pressure parts shall be plug-in type (Figure la)), dimple type (Figure 1b)) or straddle-type (Figure 1c)).
