Seelskrews & Seelbolts

In addition to fastening, our self-sealing screws and bolts offer a reliable and reusable seal, preventing (or containing!) contamination from dust, air, water, lubricants and other liquid or gaseous substances. They are also vibration resistant, making them a great choice for applications that encounter day-to-day jarring, or repetitive movement.

Should you need a more serious level of vibration resistance, our screws and bolts are available with additional locking features, such as self-locking pellets, strips and patches. Seelskrews® and Seelbolts® are available in many standard thread sizes and with various o-ring elastomer options. Some additional customizations include specialty thread-forming variations, tamper-resistant drives, thread captivation, as well as paint and finish options.

For information on maximum torque values for Seelskrews® and Seelbolts® please see our table of Torque Values for Self-Sealing Hardware.

MATERIAL SPECIFICATIONS
For APM Hexseal® Standard Seelskrews® & Seelbolts®

Screw/Bolt Material: 18/8 Stainless Steel, passivated
Threads: Imperial— Class 2A ; Metric— Class 6g
O-Ring Elastomer: Silicone conforms to A-A-59588, Class 2, GR60 or GR70, Red
Temperature Range: -80° F to +425° F ( -62° C to +219° C)
Pressure Range: Up to 20,000 psig internal and external (subject to clearance hole dimensions).
Resistant to: Splash, salt spray, sunlight, ozone, weather, fungus, dust, and most acids and lubricating oils.

† Standard for stock screws and bolts.
‡ Alternative o-ring elastomers are available. Consult our O-Ring Elastomer Options table for details.

STANDARD PAN HEAD with CROSS RECESS DRIVE (PHILLIPS) Fig.1
TYPE CODE R

Thread SizeDrive SizeMin. Length
Available (L)
Max. Head
Diameter (C)
Max. Head
Height (D)
Recommended Clearance
Hole (Min. - Max.)
2-56 UNC-2A#11/4"0.181"0.062"0.091" - 0.950"
4-40 UNC-2A#11/4"0.238"0.080"0.125" - 0.129"
6-32 UNC-2A#21/4"0.294"0.097"0.147" - 0.152"
8-32 UNC-2A#21/4"0.347"0.115"0.173" - 0.179"
10-32 UNF-2A#23/8"0.403"0.133"0.199" - 0.204"
10-24 UNC-2A#23/8"0.403"0.133"0.199" - 0.204"
1/4-20 UNC-2A#33/8"0.517"0.175"0.265" - 0.269"
1/4-28 UNF-2A#33/8"0.517"0.175"0.265" - 0.269"

METRIC PAN HEAD with CROSS RECESS DRIVE (PHILLIPS) Fig.1
TYPE CODE RM

Thread SizeDrive SizeMin. Length
Available (L)
Max. Head
Diameter (C)
Max. Head
Height (D)
Recommended Clearance
Hole (Min. - Max.)
M2 X 0.40 6g#14mm4.24mm1.60mm2.31mm - 2.41mm
M2.5 X 0.45 6g#14mm5.46mm2.10mm2.67mm - 2.84mm
M3 X 0.50 6g#24mm6.70mm2.40mm3.55mm - 3.65mm
M4 X 0.70 6g#24mm8.69mm3.05mm4.39mm - 4.54mm
M5 X 0.80 6g#26mm9.90mm3.70mm5.56mm - 5.66mm
M6 X 1 6g#36mm12.58mm4.60mm6.73mm - 6.83mm

STANDARD PAN HEAD with SLOTTED DRIVE Fig.2
TYPE CODE S

Thread SizeMin. Length
Available (L)
Max. Head
Diameter (C)
Max. Head
Height (D)
Recommended Clearance
Hole (Min. - Max.)
2-56 UNC-2A1/4"0.168"0.055"0.091" - 0.950"
4-40 UNC-2A1/4"0.220"0.069"0.125" - 0.129"
6-32 UNC-2A1/4"0.271"0.083"0.147" - 0.149"
8-32 UNC-2A1/4"0.323"0.097"0.173" - 0.177"
10-32 UNF-2A1/4"0.374"0.113"0.199" - 0.201"
10-24 UNC-2A1/4"0.374"0.113"0.199" - 0.201"
1/4-20 UNC-2A5/16"0.493"0.148"0.265" - 0.269"
1/4-28 UNF-2A5/16"0.493"0.148"0.265" - 0.269"

METRIC PAN HEAD with SLOTTED DRIVE Fig.2
TYPE CODE SM

Thread SizeMin. Length
Available (L)
Max. Head
Diameter (C)
Max. Head
Height (D)
Recommended Clearance
Hole (Min. - Max.)
M2 x 0.40 6g4mm4.24mm1.37mm2.31mm - 2.41mm
M2.5 x 0.45 6g4mm5.56mm1.73mm2.67mm - 2.84mm
M3 x 0.50 6g4mm6.22mm1.90mm3.55mm - 3.65mm
M4 x 0.70 6g4mm8.17mm2.43mm4.39mm - 4.54mm
M5 x 0.80 6g6mm9.70mm3.05mm5.56mm - 5.66mm
M6 x 1 6g6mm12.49mm3.73mm6.73mm - 6.83mm
M8 x 1.25 6g6mm15.62mm4.52mm8.45mm - 8.55mm

STANDARD FLAT HEAD with CROSS RECESS DRIVE (PHILLIPS) Fig.3
TYPE CODE SFR

Thread SizeDrive SizeMin. Length
Available (L)
Max. Head
Diameter (C)
Recommended Clearance
Hole (Min. - Max.)
2-56 UNC-2A#11/4"0.172"0.091" - 0.950"
4-40 UNC-2A#11/4"0.225"0.125" - 0.129"
6-32 UNC-2A#21/4"0.279"0.147" - 0.152"
8-32 UNC-2A#21/4"0.332"0.173" - 0.179"
10-24 UNC-2A#25/16"0.385"0.199" - 0.204"
10-32 UNF-2A#25/16"0.385"0.199" - 0.204"
1/4-20 UNC-2A#33/8"0.507"0.265" - 0.269"

STANDARD HEXAGONAL HEAD BOLT Fig.4
TYPE CODE ST

Thread SizeMin. Length
Available (L)
Distance Between
Flats (C)
Distance Between
Points (P) †
Max. Head
Height (D)
Recommended Clearance
Hole (Min. - Max.)
1/4-28 UNF-2A3/8"0.440"0.510"0.163"0.265" - 0.269"
1/4-20 UNC-2A3/8"0.440"0.510"0.163"0.265" - 0.269"
5/16-24 UNF-2A1/2"0.502"0.580"0.211"0.332" - 0.336"
5/16-18 UNC-2A3/8"0.502"0.580"0.211"0.332" - 0.336"
3/8-24 UNF-2A5/8"0.565"0.650"0.243"0.395" - 0.399"
3/8-16 UNC-2A1/2"0.565"0.650"0.243"0.395" - 0.399"
1/2-20 UNF-2A1/2"0.752"0.870"0.323"0.530" - 0.534"
1/2-13 UNC-2A3/4"0.752"0.870"0.323"0.530" - 0.534"

† The values provided for Distance Between Points are for reference only.

METRIC HEXAGONAL HEAD BOLT Fig.4
TYPE CODE STM

Thread SizeMin. Length
Available (L)
Distance Between
Flats (C)
Distance Between
Points (P) †
Max. Head
Height (D)
Recommended Clearance
Hole (Min. - Max.)
M6 X 1 6g8mm10mm11.28mm4.15mm6.73mm - 6.83mm
M8 X 1.25 6g12mm13mm14.69mm5.65mm8.45mm - 8.55mm
M10 X 1.5 6g12mm17mm19.25mm7.18mm10.53mm - 10.64mm
M12 X 1.75 6g20mm19mm21.50mm8.18mm12.79mm - 12.9mm

† The values provided for Distance Between Points are for reference only.

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