ASME B16.5 · ASTM A105 · stock and made to order
12″ Class 300 Weld Neck Flange — ASTM A105
12″ Class 300 weld neck flange to ASME B16.5, machined from ASTM A105 forging. Outside diameter 520.7 mm, thickness 49.3 mm, 16 bolt holes on a 450.8 mm circle, approximate weight 63.9 kg. Available with raised face, flat face or ring-type joint finish.
Size
12″ / DN300
Pressure class
Class 300
Outside diameter
520.7 mm
Flange thickness
49.3 mm
Bolt circle
450.8 mm
Approx. weight
63.9 kg
Full dimensions — 12″ Class 300
| NPS | DN | OD | Thickness | RF Ø | Bolt circle | Bolts | Weight |
|---|---|---|---|---|---|---|---|
| 2″ | 50 | 165.1 mm (6.5″) | 20.8 mm (0.82″) | 91.95 mm (3.62″) | 127 mm (5″) | 8 × Ø19 | 4.1 kg |
| 4″ | 100 | 254 mm (10″) | 30.2 mm (1.19″) | 157.23 mm (6.19″) | 200.2 mm (7.88″) | 8 × Ø22.4 | 11.9 kg |
| 6″ | 150 | 317.5 mm (12.5″) | 35.1 mm (1.38″) | 215.9 mm (8.5″) | 269.7 mm (10.62″) | 12 × Ø22.4 | 20.3 kg |
| 8″ | 200 | 381 mm (15″) | 39.6 mm (1.56″) | 269.75 mm (10.62″) | 330.2 mm (13″) | 12 × Ø25.4 | 31.1 kg |
| 12″ (this size) | 300 | 520.7 mm (20.5″) | 49.3 mm (1.94″) | 381 mm (15″) | 450.8 mm (17.75″) | 16 × Ø31.8 | 63.9 kg |
Dimensions in millimetres; bolt hole diameter applies to through-holes. For stud length, gasket and bolt selection, see the assembly note below.
What Class 300 means in service
ASME B16.5 Class 300 is a pressure class, not a single pressure number: the allowable pressure falls as temperature rises. For ASTM A105 in material group 1.1 the rating is 740 psi (51 bar) at 38 °C (100 °F), and the applicable value must be read from the pressure–temperature tables in B16.5 for the actual design temperature. The 12″ Class 300 weld neck flange in this page is therefore specified by size and class, and the gasket, bolting and pipe schedule are selected to match.
The 16 bolts on a 450.8 mm circle are sized to develop the gasket seating load without over-stressing the flange ring. Use the bolt hole diameter of Ø31.8 mm with a bolt one size smaller, and follow the cross-pattern tightening sequence in ASME PCC-1 for a leak-free joint.
Material and finish options
| Option | Specification | When to choose it |
|---|---|---|
| Carbon steel | ASTM A105 / A105N | General oil, gas, water and steam service |
| Low temperature | ASTM A350 LF2 | Service down to −46 °C with impact testing |
| Stainless | ASTM A182 F304/F316L | Corrosive, hygienic or marine atmosphere |
| Alloy | ASTM A182 F11/F22/F91 | High-temperature refinery and power piping |
| Duplex | ASTM A182 F51/F53 | Chloride-bearing and offshore service |
Inspection and delivery
- Dimensional inspection against the B16.5 table for this size and class
- Heat number stamped on the rim; EN 10204 3.1 certificate issued
- PMI on stainless and alloy heats; UT/RT on request
- Anti-rust oil, plywood case or pallet, with packing list and MTC
- Typical lead time 7–15 days for A105 stock sizes, 20–30 days for alloys
Other sizes in Class 300
Request a quotation
12″ Class 300 Weld Neck Flange
Tell us the quantity, face type, material and delivery port. We will confirm price, lead time and the applicable certificate within one business day.
Send an Inquiry
Send drawings, dimensions or a standard reference. Our sales engineers reply within 24 hours on business days.