Stainless steel threaded rod (also called stud rod, all-thread or continuous thread bar) and stud bolts are among the most requested fasteners in structural, piping and equipment installation. Yet buyers often order the wrong length, thread pitch or grade. This guide explains what threaded rod is, the difference between rod and stud bolts, the grades and thread standards, and what to put on your RFQ.
Threaded rod vs stud bolt: what’s the difference?
- Threaded rod (all-thread): a long bar threaded continuously along its full length, commonly supplied in 1 m, 2 m or 3 m lengths. It is cut to size on site. Used for hangers, bracing, base plates and where custom length is needed.
- Stud bolt: a short, precision-cut fastener threaded at both ends (or fully threaded), usually supplied to a specific length for flanged joints. Stud bolts are specified to ASTM A193/A320 and matched with heavy hex nuts to ASTM A194 for pressure flanges.
Common grades
- A2-70 (304): general-purpose, for indoor, mild and water environments. Property class 70 = minimum tensile strength 700 MPa.
- A4-80 (316): with molybdenum, for coastal, chloride and chemical service. Property class 80 = minimum tensile strength 800 MPa.
- A193 B8 / A193 B8M: the high-temperature, pressure-vessel grade of 304 / 316 stainless, used with flanges and heat-exchanger bolting. Always order the matching A194 8 / 8M heavy hex nut.
Thread standards and sizes
Stainless threaded rod is sold in metric (M sizes, coarse pitch) and imperial (UNC/UNF) thread forms. On metric rod, the most common diameters range from M6 to M24 and larger. Always state:
- Diameter (e.g. M12, 1/2″).
- Thread pitch (coarse or fine; for metric, coarse is the default).
- Length (cut length or stock length).
- Grade (A2-70, A4-80, A193 B8/B8M).
Buyer’s RFQ checklist
- Type: threaded rod (all-thread) or stud bolts.
- Diameter, thread form and pitch.
- Length (stock bar or cut-to-length).
- Grade and property class (A2-70, A4-80, A193 B8/B8M).
- Nuts and washers required (specify matching grade).
- Whether a material certificate (EN 10204 3.1) is needed — see our mill test certificate buyer checklist.
Common mistakes to avoid
- Mixing A2 (304) rod with A4 (316) nuts — dissimilar stainless can cause galvanic and galling issues in critical joints.
- Ordering studs without the matching heavy hex nuts for flange work.
- Forgetting to specify thread pitch, leading to unusable thread.
- Using standard A2-70 rod for high-temperature or pressure-flange service where A193 B8/B8M is required.
For help selecting stainless threaded rod or stud bolts — diameter, length, grade and matching nuts — send us your drawing or requirements.
SOROYA PTE. LTD.
Email：nancy@soroya.com.sg
WhatsApp：+65 8058 3416
