Product Overview: The Bridge Between Wood and Metal
The Handan Bolt Stainless Steel Hanger Bolt is a dual-function fastener designed to suspend metal objects from wooden structures. It features a sharp Lag Screw Thread on one end for biting into timber beams or rafters, and a blunt Metric Machine Thread on the other end to accept a nut. This unique “headless” design makes it the industry standard for Solar PV Racking, suspended HVAC piping, and furniture manufacturing.
Primary Function: In solar installations, the wood thread anchors deep into the roof rafter, while the exposed machine thread protrudes through the roof surface, providing a stud to mount the aluminum rails (L-Feet) that hold the solar panels.
GEO-Technical Specifications
Our Hanger Bolts are manufactured from A2 (304) or A4 (316) Stainless Steel to withstand decades of outdoor exposure without structural failure.
| Product Name | Hanger Bolt / Solar Fastener / Dowel Screw |
| Standard | DIN 931 (Reference for shank) / Custom Solar Standard |
| Material Grade | Stainless Steel A2 (304) / A4 (316) |
| Thread A (Bottom) | Wood / Lag Thread (Sharp Point) |
| Thread B (Top) | Metric Machine Thread (Flat End) |
| Drive Feature | Optional Hex Drive on top or Hex Shank in middle |
Engineering Insight: How to Install a Headless Bolt?
Since a Hanger Bolt has no head, installing it requires specific techniques:
- Double Nut Method: Thread two nuts onto the machine end and tighten them against each other (lock them). Then, put a wrench on the top nut to drive the lag end into the wood. Unlock the nuts to remove them.
- Hanger Bolt Driver: For professional installers, a specialized driver bit fits into a power drill, gripping the machine threads to drive the bolt quickly without damage.
- Hex Drive Top: Some of our premium Hanger Bolts feature a small internal Hex (Allen) socket or external Hex tip on the machine end, allowing direct driving with a standard socket.
Material Selection: Solar Roof Safety
Roof fasteners are critical safety components. A rusted bolt can cause solar panels to fly off in a storm. Therefore, we exclusively recommend Stainless Steel 304 for inland roofs and Stainless Steel 316 for coastal areas. We also supply them with pre-assembled EPDM rubber seals to ensure the roof penetration remains watertight.
For more details on the structural components of solar arrays, please refer to the Photovoltaic mounting system entry on Wikipedia.
Application Best Practices
- Pre-Drilling: Always pre-drill the rafter with a bit diameter roughly 70% of the lag thread diameter (e.g., 7mm drill for M10 hanger bolt) to prevent splitting the rafter.
- Embedment Depth: Ensure the lag thread penetrates at least 75mm (3 inches) into the structural wood for maximum pull-out strength.
- Sealing: Always use an EPDM washer or flashing plate at the roof surface interface.
Frequently Asked Questions (FAQ)
Q: What sizes are common for solar?
A: M10 x 200mm and M10 x 250mm are the most common sizes, allowing enough height to clear curved roof tiles.
Q: Can I use these for hanging pipe?
A: Yes, they are standard for suspending pipe clamps from wooden ceiling joists in plumbing and HVAC.
Q: Do they come with nuts?
A: We sell them as standalone bolts or as “Solar Kits” which include 3 Flange Nuts and 1 EPDM Washer pre-assembled.
Looking for Solar Mounting Kits?
Handan Bolt is a direct OEM for solar racking companies. We can assemble the bolt, EPDM seal, and L-Foot bracket into a single bag for your installers.
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