S9086-CJ-STM-010/CH-075R2 REVISION 2 NAVAL SHIPS’ TECHNICAL MANUAL CHAPTER 075 FASTENERS THIS CHAPTER SUPERSEDES NSTM CHAPTER 075 DATED 15 SEPTEMBER 1997 DISTRIBUTION STATEMENT A: APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. PUBLISHED BY DIRECTION OF COMMANDER, NAVAL SEA SYSTEMS COMMAND 1 DEC 1997 TITLE-1 @@FIpgtype@@TITLE@@!FIpgtype@@ S9086-CJ-STM-010/CH-075R2 Certificaton Sheet TITLE-2 S9086-CJ-STM-010/CH-075R2 TABLE OF CONTENTS Chapter/Paragraph Page 075 FASTENERS ....................................... 75-1 SECTION 1. INTRODUCTION TO THREADED FASTENERS ................. 75-1 075-1.1 SCOPE ........................................... 75-1 075-1.1.1 GENERAL. .................................... 75-1 075-1.1.2 REFERENCE DOCUMENTS. .......................... 75-1 075-1.2 GENERAL ......................................... 75-2 075-1.2.1 USING FASTENERS. .............................. 75-2 075-1.2.2 FASTENER MAINTENANCE PRACTICES. ................. 75-3 075-1.2.3 HI SHOCK. .................................... 75-3 075-1.2.4 GLOSSARY OF TERMS. ............................ 75-4 SECTION 2. IDENTIFICATION OF FASTENERS ......................... 75-7 075-2.1 GENERAL ......................................... 75-7 075-2.2 THREAD CLASS, FIT, SERIES, AND DESIGNATION ................ 75-8 075-2.2.1 THREAD CLASSES. ............................... 75-8 075-2.2.1.1 Class 1. ................................ 75-8 075-2.2.1.2 Class 2. ................................ 75-8 075-2.2.1.3 Class 3. ................................ 75-8 075-2.2.1.4 Class 5. ................................ 75-8 075-2.2.2 THREAD FIT. ................................... 75-8 075-2.2.2.1 Class 1, 2, and 3 Fit. ........................ 75-8 075-2.2.2.2 Class 5 Fit. .............................. 75-9 075-2.2.3 THREAD SERIES. ................................ 75-9 075-2.2.3.1 UNC (Coarse Thread) Series. .................... 75-9 075-2.2.3.2 UNF (Fine Thread) Series. ..................... 75-9 075-2.2.3.3 UN (Constant Pitch Thread) Series. ................ 75-9 075-2.2.3.4 UNJ. ................................. 75-9 075-2.2.3.5 NC (National Coarse Thread) Series. ............... 75-9 075-2.2.4 THREAD DESIGNATION. ........................... 75-9 075-2.2.5 THREAD ACCEPTABILITY, GAUGING. ................... 75-10 075-2.2.5.1 Fastener Fit Requirements. ..................... 75-10 075-2.2.6 THREAD GAUGES. ............................... 75-10 075-2.3 IDENTIFYING REPLACEMENT FASTENERS .................... 75-11 075-2.3.1 DRAWING IDENTIFICATION REQUIREMENTS. .............. 75-11 075-2.3.2 IDENTIFYING FASTENERS ON APL’S. ................... 75-12 075-2.3.3 IDENTIFYING FASTENERS AND FASTENER STANDARD PART NUMBERS WHEN SUPPORT DOCUMENTATION IS LACKING. 75-12 075-2.4 CAPSCREWS AND INTERNAL WRENCHING BOLTS ............... 75-14 075-2.4.1 SOCKET-HEAD CAP SCREWS. ........................ 75-14 i S9086-CJ-STM-010/CH-075R2 TABLE OF CONTENTS - Continued Chapter/Paragraph Page 075-2.4.1.1 Selecting Dimensional Standard .................. 75-14 075-2.4.1.2 NAS 1351 and NAS 1352 Part Numbers. ............. 75-18 075-2.4.1.3 Authorized Socket-Head Capscrew Substitutions. ......... 75-19 075-2.4.1.4 Socket-Head Capscrew Substitution Requiring NAVSEA Approval. ............................. 75-20 075-2.4.1.5 Identification of Socket Head Cap Screws. ............ 75-20 075-2.4.2 INTERNAL WRENCHING BOLTS. ...................... 75-21 075-2.4.2.1 Distinguishing Internal Wrenching Bolts from Socket-Head Capscrews. ............................ 75-21 075-2.4.2.2 Identification Marking of Internal Wrenching Bolts. ....... 75-21 075-2.4.2.3 Restrictions on Using Internal Wrenching Bolts. ......... 75-21 075-2.4.3 HEXAGON-HEAD CAPSCREWS. ....................... 75-22 075-2.4.3.1 ASME B 18.2.1 Part Numbering System. ............. 75-22 075-2.4.3.2 Zinc and Cadmium Plated Hex Head Cap Screws. ........ 75-23 075-2.4.3.3 Restrictions on the Use of Grade 8, Zinc Plated Hex Head Cap Screws. .............................. 75-26 075-2.5 WASHERS ......................................... 75-26 075-2.5.1 IDENTIFYING REPLACEMENT WASHERS. ................. 75-26 075-2.5.2 COUNTERSUNK WASHERS (SINGLE SURFACE). ............. 75-27 075-2.5.3 COUNTERSUNK WASHERS (TWO SURFACES). .............. 75-27 075-2.5.4 LOCKWASHERS. ................................ 75-27 075-2.6 ZINC-PLATED STEEL NUTS AND WASHERS .................... 75-27 075-2.7 THREAD INSERTS .................................... 75-27 075-2.7.1 PURPOSE OF THREAD INSERT. ....................... 75-27 075-2.8 NONSTANDARD FASTENER APPLICATIONS .................... 75-28 075-2.8.1 LEFT-HAND THREAD APPLICATIONS. ................... 75-28 075-2.8.2 UNIFORM STRENGTH FASTENERS. ..................... 75-30 075-2.8.2.1 Bolt-Studs. .............................. 75-30 075-2.8.3 HOLES FOR UNIFORM STRENGTH FASTENERS. ............. 75-31 SECTION 3. THREADED FASTENER MATERIALS AND MARKING ............. 75-35 075-3.1 GENERAL ......................................... 75-35 075-3.2 MATERIAL REQUIREMENTS AND SPECIFICATIONS ............... 75-35 075-3.2.1 FASTENER REQUIREMENTS FOR MIC LEVEL I APPLICATIONS. 75-35 075-3.2.2 LEVEL I REQUIREMENTS FOR FASTENERS. ............... 75-35 075-3.2.2.1 Procurement Specifications. ..................... 75-35 075-3.2.2.2 Fastener Identification and Control. ................ 75-35 075-3.2.2.3 Color Coding. ............................ 75-36 075-3.2.3 FASTENER MATERIAL CHARACTERISTICS, IDENTIFICATION MARKINGS AND SUGGESTED USE. ................... 75-36 075-3.2.3.1 Chemical and Physical Properties. ................. 75-36 ii S9086-CJ-STM-010/CH-075R2 TABLE OF CONTENTS - Continued Chapter/Paragraph Page 075-3.2.3.2 Material Identification Markings. .................. 75-36 075-3.2.3.3 Material Identification Markings for Stainless Steel Fasteners. 75-37 075-3.2.3.4 Identifying Material When Fasteners Are Not Marked. ...... 75-37 075-3.2.3.5 Manufacturer’s Markings. ...................... 75-37 075-3.3 MIL-S-1222 FASTENERS. ................................ 75-37 075-3.3.1 BACKGROUND. ................................. 75-37 075-3.3.2 MIL-S-1222 FASTENER MATERIAL MARKING. .............. 75-38 075-3.3.2.1 300 Series Stainless. ......................... 75-38 075-3.3.2.2 400 Series Stainless Steel. ..................... 75-38 075-3.3.2.3 Marking Locations. ......................... 75-38 075-3.3.3 AVAILABILITY .................................. 75-39 075-3.3.3.1 Fastener Part Numbers. ....................... 75-39 075-3.3.3.2 Other Sources. ............................ 75-39 075-3.4 ISSUES AFFECTING MATERiAL SELECTION .................... 75-58 075-3.4.1 CORROSION. ................................... 75-58 075-3.4.1.1 Oxidation. .............................. 75-58 075-3.4.1.2 Galvanic Corrosion. ......................... 75-58 075-3.4.1.3 Design Considerations to Reduce or Eliminate Corrosion. .... 75-59 075-3.4.2 HYDROGEN EMBRITTLEMENT AND STRESS CORROSION CRACKING. .................................. 75-60 075-3.4.2.1 High-Strength Steel Fasteners. ................... 75-60 075-3.4.3 COATINGS. .................................... 75-62 075-3.4.3.1 Corrosion Protection. ........................ 75-62 075-3.4.3.2 Zinc and Cadmium Coatings. .................... 75-63 075-3.4.3.3 Black Oxide Coated Fasteners. ................... 75-63 075-3.4.3.4 Zinc Primer Coating in Accordance with DOD-P-24648. .... 75-64 075-3.4.3.5 Metallic-Ceramic Coated Fasteners. ................ 75-66 075-3.5 HIGH-TEMPERATURE FASTENERS .......................... 75-66 075-3.6 SUITABLE USES FOR THREADED FASTENERS .................. 75-67 075-3.7 TELEPHONE NUMBERS AND POINTS OF CONTACT ............... 75-69 075-3.7.1 NAVSEA. ..................................... 75-69 075-3.7.2 DISC. ....................................... 75-69 075-3.7.3 NAVICP-M-P (NAVAL INVENTORY CONTROL POINT), FORMERLY SPCC (SHIPS PARTS CONTROL CENTER). ............... 75-69 SECTION 4. FASTENER TIGHTENING ............................... 75-71 075-4.1 GENERAL ......................................... 75-71 075-4.2 TIGHTENING SEQUENCE ............................... 75-72 075-4.3 PRELOAD ......................................... 75-72 iii S9086-CJ-STM-010/CH-075R2 TABLE OF CONTENTS - Continued Chapter/Paragraph Page 075-4.3.1 PRELOAD THEORY. ............................... 75-72 075-4.3.2 PURPOSE OF PRELOAD. ............................ 75-72 075-4.3.2.1 Preventing Loosening. ........................ 75-73 075-4.3.2.2 Improving Fastener Fatigue Life. .................. 75-73 075-4.3.3 DETERMINING PROPER PRELOAD. ..................... 75-74 075-4.3.3.1 Determining Design Operating Loads. ............... 75-77 075-4.3.3.2 Determining Torque Requirements. ................. 75-77 075-4.4 RELAXATION ....................................... 75-77 075-4.4.1 General. ...................................... 75-77 075-4.4.2 INITIAL RELAXATION. ............................ 75-77 075-4.4.3 TORSIONAL RELAXATION. .......................... 75-78 075-4.4.4 LONG TERM RELAXATION. ......................... 75-78 075-4.4.4.1 Stress Relaxation. .......................... 75-78 075-4.4.4.2 Vibration Relaxation. ........................ 75-78 075-4.5 Methods of establishing preload ............................. 75-78 075-4.5.1 TORQUE CONTROL. .............................. 75-79 075-4.5.1.1 Units of Measurement. ....................... 75-79 075-4.5.1.2 Determining Required Torque. ................... 75-79 075-4.5.1.3 Applying Torque to a Fastener. ................... 75-81 075-4.5.1.4 Torque Wrenches. .........................