Type A Stud Bolt
Galvanised class 8.8 AS 2528 Type A stud bolts for bolting pipe flanges together, M16 and M20.
About the Type A Stud Bolt
Type A stud bolts are used with two nuts to bolt pipe flanges together on pipelines and process plant. They are hot dip galvanised class 8.8 to AS 2528 Type A, threaded full length with 45° chamfered ends, in M16 x 70 and 75mm and M20 x 90, 95 and 100mm; Hobson gives an application range of -50°C to 300°C. Choose the size and length above; the guide below covers what Type A means, nuts, the galvanised coating and how they differ from B7 studs.
Also called AS 2528 Type A studs, fully threaded studbolts or galvanised flange studs.
Features
- AS 2528 Type A stud bolts
- Class 8.8
- Hot dip galvanised
- M16 (2.0 pitch) x 70 and 75mm; M20 (2.5 pitch) x 90, 95 and 100mm
Applications
- Bolting pipe flanges together
- Pipelines and process plant
What a Type A stud is
A stud bolt has no head: it is a length of threaded bar with a nut run onto each end, so a flange joint can be clamped from both sides. Hobson lists these for flange bolting. Its Did You Know sheet describes them as Type A, fully threaded (referring to AS 2528), with 45° chamfered ends.
They are metric (M16 and M20, standard coarse pitch), class 8.8 and hot dip galvanised. Hobson gives an application temperature range of -50°C to 300°C for them, and test reports with full independent decarburisation test results are available from Hobson.
Type A stud sizes
Every Type A stud bolt we carry. Select a row to open that size and length.
Size as diameter x length in mm, as in the selector. Thread pitch from our product data (M16 = 2.0mm, M20 = 2.5mm, standard coarse). Packs are the minimum order. Tap a number to show it in the selector above.
Class 8.8 strength
Class 8.8 is a metric property class for medium carbon steel, quenched and tempered. Hobson's head markings article gives these minimums for class 8.8 from M16 up, which covers both sizes here: proof load stress 600MPa, yield strength 660MPa and tensile strength 830MPa. They are material property values, not working loads. Hobson publishes no working load, pressure rating or tightening torque for these studs; the bolt load for a flange comes from the piping or flange specification and the engineer.
Type A (AS 2528) or B7 studs?
- These Type A studs: metric M16 and M20, AS 2528 class 8.8, hot dip galvanised, -50°C to 300°C per Hobson.
- Petrochemical stud bolts on our stud bolt page: inch sizes (1/2 to 2 inch UNC and 8 UN) to ASTM A193 grade B7 or stainless B8 and B8M Class 2, in plain, Xylan blue, galvanised, zinc, cadmium and other coatings, with ASTM A194 heavy hex nuts.
- Hobson's petrochemical property, torque and flange bolting tables are for those ASTM inch studs. They do not apply to these metric class 8.8 studs, so do not take a torque or a load from them for Type A studs.
- Which one a job needs is set by the flange standard and the piping specification, not by the stud that fits the holes.
Nuts and washers for Type A studs
The studs are sold on their own, so order two nuts per stud. In M16 and M20 we have hot dip galvanised class 8 hex nuts (AS 1112.1) on the hex nut page, and ASTM A194M grade 2H hot dip galvanised heavy hex nuts, which Hobson labels oversize, on the heavy hex nut page. The nut grade, coating and any washers for the joint come from the flange or piping specification: match them to it, and keep the coating the same as the stud.
Hot dip galvanised finish
- Hot dip galvanised to AS/NZS 1214, 50 microns, rated high corrosion resistance in Hobson's finish comparison and recommended for long term outdoor applications.
- Exposed sites: Hobson's corrosion guide (written for metal connectors) lists hot dip galvanising or stainless for exposed positions in low, medium (coastal) and industrial zones, but stainless steel in the sea spray zone and 316 within 2m of a pool. For those sites ask us about a stainless option.
- A matt grey look is normal. Hobson's article on galvanising explains that a newer process gives a duller finish than the old lustrous one with the same physical properties, and quotes the Galvanizers Association of Australia that brightness has no effect on performance: corrosion life depends on coating mass.
Fitting Type A studs to a flange
- Check the flange or piping specification for the stud diameter, length, class, nut and washer, and the tightening method. Hobson says tightening of pipe flange stud bolts can really only be specified by engineers in the industry, because flange types, gaskets and temperatures vary.
- Run a nut onto one end of each stud.
- Pass the studs through both flanges with the gasket in place and fit the second nut on each, leaving thread through each nut.
- Tighten in the sequence and to the load or torque in the specification. Do not use Hobson's petrochemical torque table for these metric studs: it is for ASTM inch studs.
Type A studs in Adelaide
Allmat supplies galvanised Type A stud bolts with the nuts and washers to suit, plus ASTM stud bolts and heavy hex nuts, to maintenance crews, pipe fitters and fabricators across Adelaide and South Australia. Send us the flange schedule or your list and we will price the lot.
Type A studs and nuts for flange work
Galvanised Type A stud bolts, nuts and washers are available to order from Allmat for maintenance crews, pipe fitters, fabricators, water and process plant contractors across Adelaide and South Australia. Order through Allmat, we pick and pack it, then click and collect from the Allmat yard or have it delivered to site.
Goes with
Questions
What is a Type A stud?
Hobson describes its Type A stud bolt as fully threaded, referring to AS 2528, with 45° chamfered ends. It has no head; a nut goes on each end, and it is used for flange bolting.
What sizes of Type A stud do you have?
M16 x 70 and 75mm (packs of 25) and M20 x 90, 95 and 100mm (packs of 20), all hot dip galvanised class 8.8 with standard coarse threads.
What temperature can Type A studs be used at?
Hobson gives an application temperature range of -50°C to 300°C for these studs. The gasket, nuts and the rest of the joint have their own limits, which the piping specification sets.
How strong is a class 8.8 stud?
Hobson's head markings article gives class 8.8 from M16 up a minimum tensile strength of 830MPa, yield strength of 660MPa and proof load stress of 600MPa. Those are material minimums, not working loads; Hobson publishes no working load or torque for these studs.
Are Type A studs the same as B7 studs?
No. These are metric AS 2528 class 8.8 studs, hot dip galvanised. B7 studs are inch sizes to ASTM A193 in a chrome-moly alloy, and are on our stud bolt page with ASTM A194 heavy hex nuts.
What nuts go with Type A studs?
The nut the flange or piping specification calls for. In M16 and M20 we have hot dip galvanised class 8 hex nuts (AS 1112.1) and hot dip galvanised ASTM A194M 2H heavy hex nuts, which Hobson labels oversize.
Where can I buy Type A studs in Adelaide?
Order through Allmat. Order ahead by phone on 1300 03 03 63 or send your list for a quote, then click and collect from 25 Kapara Road, Gillman, or have them delivered to site.
Type A Stud Bolt: sizes and finishes we supply
5 lines by type and finish. Pick one above for its product code and pack sizes.
| Type | Finish | Sizes | Lengths | Lines |
|---|---|---|---|---|
| Type A stud bolt | Hot Dip Galvanised | M16, M20 | 70, 75, 90, 95, 100 | 5 |
Data sheets and documents
The documents for the product you choose are listed with the selector above. Here is every Type A Stud Bolt document from Hobson Engineering.
All Type A Stud Bolt documents (8)
Data sheets and technical data (5)
Did You Know flyers (1)
Guides and articles (2)
Need them in bulk?
Add the sizes you need to your quote, or send us your list and we’ll price the lot and supply it with the rest of your order.
Browse all stud bolts & nuts