Bolted vs Welded Steel Connections: Pros, Cons and Uses
Bolted and welded steel connections compared: shop welding vs site bolting, bolt grades 8.8 and 10.9, preloaded bolts, inspection, cost and erection speed.
Saudi Steel Work Editorial Team · · 3 min read
Short answer: Most steel structures are shop-welded and site-bolted: welding is done in controlled workshop conditions where quality is easier to achieve, and bolting is used on site because it is faster, needs less specialised labour and is easier to inspect. Site welding is used where bolting is impractical or for continuity.
Connections can account for a significant share of steelwork cost and a large part of erection time. Choosing between bolting and welding affects fabrication, erection speed and inspection.
The usual approach: shop weld, site bolt
- In the shop, welding of end plates, fin plates, stiffeners and base plates is done under controlled conditions with qualified procedures.
- On site, members are connected with bolts — faster, safer and less weather-dependent.
Bolted connections
Advantages
- Fast erection with smaller crews
- Easier inspection (bolt counts, torque or tension checks)
- No hot work permits on site
- Easier to dismantle or modify
Considerations
- Holes must be accurately drilled or punched
- Tolerances must be controlled
- Preloaded bolts need controlled tightening and verification
Common bolt grades: 8.8 and 10.9 (ISO), or ASTM A325/A490 (now F3125 grades) in American practice.
Welded connections
Advantages
- Continuous, rigid connections
- Clean appearance — no bolt heads
- No hole deductions in members
Considerations
- Site welding needs qualified welders, power, weather protection and NDT
- Slower and more expensive on site
- Heat input can distort members
See welding processes compared and WPS, PQR and welder qualification.
Typical connection types
| Connection | Usually |
|---|---|
| Beam-to-column simple shear | Fin plate or end plate, bolted |
| Moment connection | Extended end plate bolted, or site-welded flanges |
| Column splice | Bolted cover plates or end plates |
| Base plate | Shop-welded plate, anchor bolts on site |
| Bracing | Gusset plates, bolted |
Saudi site factors
Summer heat and midday work restrictions favour bolting on site. Coastal humidity makes protecting site welds harder, while bolted joints can be pre-coated in the shop.
Need connections designed and fabricated? See structural steel fabrication.