ASME B18.18.1 pdf download Inspection and Quality Assurance for General Purpose Fasteners
1 GENERAL INFORMATION
1.1 Basic Plan Structure
This Standard outlines a Quality Assurance Plan forinternally and externally threaded fasteners and accessories or associated parts.Provisions are included forsampling plans,inspection frequencies, control proce-dures, and record keeping.
Included in this plan are fasteners for general purposeapplications, such as those where hand assembly isemployed and cost is probably of prime consideration.This plan relies on judicious manufacturing controls andinspections by the producer and, should a dispute arise,provides an inspection plan for lot compliance aftershipment.
This Standard will be used in conjunction with otheraccepted standards for product, testing, gaging, andmaterial; therefore, those provisions, as well as packaging, are not included herein.
1.2 Inspection Levels
The substantial difference in importance to the userof various characteristics and the dissimilar degrees ofcontrol in manufacture make impractical the subjectingof all characteristics to the same degree of inspection.Therefore, three inspection levels have been providedAny additional characteristics deemed applicable bythe user that do not appear in the plan shall be explicitldesignated by the user, preferably on engineering drawings and related specifications by the appropriate codeletter at the time of ordering (see Nonmandatory Appendix B)To assist in arriving at the most appropriateinspection levelthe Decision Table included in Non-mandatory Appendix A is recommended for quidance
1.3 Lot Sizes
When the acceptance number for sampling by attri-butes is fixed, variation in sample size results in variationof acceptable quality.Therefore to avoid this inconsist-ency, fixed sample sizes are applied for the greatest rangeoflot size. Sample sizes for lots up to 250,000 pieces areshown in Table 1; however, for lot sizes exceeding250,000 pieces, Table 1, Note (2) shall apply.
1.4 Measuring and Testing Equipment
All inspection and testing equipment shall be cali-brated and traceable to the National Institute of Stan-dards and Technology (NIST) standard or an equivalent national or international Standard.All calibration procedures shall comply with the requirements of ISO 17025General Requirements for the Competence of Testingand Calibration Laboratories.
1.5 Basic Plan Outline
The basic plan outline as shown in Fig. 1 is includedto enhance understanding and use.
The following is a list of publications referenced inthis Standard.