一 ,Basic structural differences
1. Double End Stud (Double-Ended Stud / Equal Thread Stud)
- Structure: Threads only on two ends, smooth unthreaded shank in the middle, no head
- Standard: GB/T 901, ASME B18.31.2 Double End Type
- Feature: Fixed grip length determined by plain shank; can't adjust clamping range freely
2. Fully Threaded Stud (Continuous Thread Stud / Full Thread Stud Bolt)
- Structure: Entire rod covered by uniform thread, zero smooth shank from end to end
- Standard: HG/T 20613, GB/T 9125, ASME B18.31.2 Continuous Thread Type
- Feature: Adjustable clamping length; match different flange thickness, multi-layer gaskets
二 ,Comparison of standards and materials
三,Mechanical Performance & Stress Feature
1. Double End Stud
- Stress concentration exists at thread-shank transition; easy fatigue failure under cyclic vibration
- Plain shank limits elastic deformation; poor anti-creep performance under long high temperature
- Only two thread sections bear load, uneven force distribution
2. Fully Threaded Stud
- No abrupt shank transition, uniform stress distribution along the whole length
- Strong anti-fatigue & anti-creep performance, stable pre-tightening force under temperature cycle
- Whole thread shares tension; sealing reliability far higher for high-pressure flanges
四,Application Scenarios
Double End Stud Suitable Scenarios (PN ≤40, Low/Medium Pressure)
- General mechanical equipment, low-pressure water/air pipelines
- Building steel structure, ordinary equipment shell, engine cylinder head
- Frequently disassembled low-risk equipment, non-toxic & non-flammable medium
- Fixed-thickness connection where grip length does not change
Fully Threaded Stud Mandatory Scenarios (PN＞40, Extreme Working Condition)
- Petrochemical, oil & gas, LNG, high-pressure valve flanges
- Pressure vessels, heat exchangers, high-temperature reactor equipment
- Marine offshore wind power, salt fog corrosion heavy industry
- Toxic, flammable, explosive medium pipeline (strict anti-leak requirement)
- Variable-thickness flanges, multi-layer composite gaskets, adjustable clamping distance
五,How to choose a product?
1. Working pressure ≤ PN40, clean non-hazardous medium, fixed connection thickness → Choose Double End Stud to save cost
2. Working pressure＞PN40, high temperature, vibration, toxic/flammable medium, variable flange thickness → Must use Fully Threaded Stud
3. Offshore, coastal salt fog, chemical corrosion environment: Fully threaded stainless steel stud (A193 B8M 316) with Ruspert coating
4. High-temperature furnace, thermal cycle equipment: A193 B7 fully threaded stud with 2H heavy nut
Handan Jihao Fasteners Co., Ltd. specializes in producing a full range of fully threaded studs and double-ended studs. We also accept custom orders for non-standard fasteners and bolt and nut sets.
For inquiries or quotes, please contact us:
WhatsApp: +8613111607537
Email: baiyanyun219@gmail.com