AIA/NAS 1351-2009 pdf download SCREW, CAP, SOCKET HEAD, UNDRILLED AND DRILLED, PLAIN AND SELF-LOCKING, ALLOY STEEL, CORROSION-RESISTANT STEEL AND HEAT-RESISTANT STEEL, UNRF-3A
(a) “M” MIN. (5 THREAD PITCHES) = REGION OF MINIMUM ENGAGEMENT WITH FULL FEMALE THREAD REQUIRED TO MEET MIL-DTL-1 8240 REQUIREMENTS.
LOCKING ELEMENT WITHIN “M” REGION MUST DEVELOP REQUIRED TORQUE WHEN TESTED IN ACCORDANCE WITH MIL-DTL-1 8240.
LENGTH OR DIAMETER OF LOCKING ELEMENT MAY BE MORE OR LESS THAN “M” PROVIDING ALL OTHER REQUIREMENTS ARE MET.
(b) “N” = ONE (1 ) COMPLETE THREAD PLUS UNTHREADED PORTION OF END. FOR EASE OF STARTING, LOCKING ELEMENT SHALL NOT BE EFFECTIVE WITHIN THIS AREA.
(c) SCREWS WHICH HAVE A LENGTH LESS THAN THE MINIMUM BASIC THREAD LENGTH, SHALL BE THREADED AS CLOSE TO HEAD AS PRACTICABLE. FOR SCREWS WHICH HAVE A LENGTH GREATER THAN THE MINIMUM BASIC THREAD LENGTH, THE BODY AND GRIP LENGTH SHALL BE IN ACCORDANCE WITH ASME B1 8.3.
(d) DRILLED HOLE DATA IN ACCORDANCE WITH PROCUREMENT SPEC FF-S-86.
PARTS SHALL HAVE DRILLED HEADS IF SPECIFIED BY CODE H.
SCREW SIZES 04 AND 06 SHALL HAVE TWO (2) DRILLED HOLES SPACED 1 80°.
SCREW SIZES 08 THRU 1 6 SHALL HAVE SIX (6) DRILLED HOLES SPACED 60°.
(DRILLED HOLES NOT APPLICABLE TO SCREW SIZES BELOW 04).
(e) IDENTIFICATION LETTER “N” IMPRESSED ON THE TOP OR SIDE OF THE HEAD, FOR SCREW SIZES 04 AND LARGER ONLY, TO DENOTE HEAT-RESISTANT STEEL.
(f) THE INTERSECTION OF THE TOP AND SIDE OF THE HEAD MAY BE CHAMFERED OR RADIUSED AT THE MANUFACTURER’S OPTION PER ASME B1 8.3.
(g) THE FILLET SHALL BE IN ACCORDANCE WITH ASME B1 8.3.
(h) MINIMUM BREAKING STRENGTH VALUES ARE BASED ON 1 80 KSI HEAT TREATMENT. LINED THROUGH STRENGTH VALUES WERE BASED ON 1 70 KSI.
HEAT-RESISTANT STEEL – SILVER FLASH IN ACCORDANCE WITH AMS2411 .
– PASSIVATE IN ACCORDANCE WITH AMS2700, METHOD 1, TYPE 2 OR TYPE 8, CLASS 1 .
– BLACK OXIDE IN ACCORDANCE WITH MIL-DTL-1 3924, CLASS 3.
– CADMIUM PLATE IN ACCORDANCE WITH AMS-QQ-P-41 6, TYPE II, CLASS 2.
CODE: MATERIAL CODE AFTER BASIC NUMBER. “-” = ALLOY STEEL.
“C” = CORROSION-RESISTANT STEEL.
“N” = HEAT-RESISTANT STEEL.
FIRST DASH NUMBER DESIGNATES SCREW THREAD SIZE AS TABULATED.

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