Pro-werks Weld-On Fill Cap Bung
Weld-On Bung Specifications
1-5/8 Inch Aluminum Weld Bung
1-1/4-12 Straight Thread
1-5/8 in. Outside Diameter Bung
Fits 1-5/8 in. Easy Turn Fill Caps
1-5/8 Inch Steel and Stainless Steel Weld Bung
1-1/4-12 Straight Thread
1-1/2 in. Outside Diameter Bung
Fits 1-5/8 in. Easy Turn Fill Caps
2 Inch Aluminum Weld Bung
1-1/2-12 Straight Thread
2 in. Outside Diameter Bung
Fits 2 in. Easy Turn Fill Caps
2 Inch Steel Weld Bung
1-1/2-12 Straight Thread
1-3/4 in. Outside Diameter Bung
Fits 2 in. Easy Turn Fill Caps
2-3/4 Inch Aluminum Weld Bung
2-1/4-10 Straight Thread
2-3/4 in. Outside Diameter Bung
Fits 2-3/4 in. Easy Turn Fill Caps
2-3/4 Inch Steel Weld Bung
2-1/4-10 Straight Thread
2-3/4 in. Outside Diameter Bung
Fits 2-3/4 in. Easy Turn Fill Caps
4-1/4 Inch Aluminum Weld Bung
3-3/4-8 Straight Thread
4-3/8 in. Outside Diameter Bung
Fits 4-1/4 in. Easy Turn Fill Caps
4-1/4 Inch Steel Weld Bung
3-3/4-8 Straight Thread
4-3/8 in. Outside Diameter Bung
Fits 4-1/4 in. Easy Turn Fill Caps
Weld-On Bung Overview
Pro-werks Fill Cap Bungs are available separately without the cap. This selection of weld-able bungs includes several different heights; available in Steel, Aluminum or Stainless Steel materials.
Precision machined and weld-able with ample cross section to assist in reducing potential distortion from welding, and sized properly for the "radially squeezed" O-ring standard of the Pro-werks Easy Turn Fill Cap. Backed by The Chassis Shop's Satisfaction Guarantee.
The bolt-on style bung selection is also available, and do not require welding; select anodized colors are available and include mounting hardware - so you won't need to run all over town looking for it!
Get a Step Ahead
Your fabricator will appreciate the stepped shoulder at the base of the bung, it serves as a positioning locator. This feature holds the bung in place while welding in a hole of a flat surface, or in the end of tubing when constructing a filler neck extension.
Note: Welding should always be performed by a qualified welder.

Perfect for Custom Tank Fabrication


Great Filler Caps - Great Colors
To compliment the color coordination of your project, the caps are finished off in Pro-Werks Brilliance anodized colors in your choice of Black, Red, Blue, or beautifully Micro-Polished aluminum – the Pro-werks Jewelry Quality finishes are unmatched and impeccable!

The Right Size Fill Cap Matters
Easy Turn Fill Caps come in many sizes and are packaged as complete assemblies with your choice of one of the many versatile mounting options, or each component is also available separately.

Proudly Made in the USA
Both the cap and bung are precision CNC machined light weight billet aluminum, right here in the USA.
Be sure to check out the entire line up - Billet aluminum Easy Turn Fill Caps are a Pro-werks specialty.
You can always count on Pro-werks to do it right!

Customer Comments:
"I use your bolt on caps and bungs on my carbon fiber Cummins common rail valve covers. Love the quality. Thank you."
– Randy Davis, Owner of OldSkoolFab, Inc.
"I upgraded my fuel cell to an Easy Turn fill cap assembly. It wasn't long until all my friends did the same. Great product!"
– As shared with us at the PRI Show
Questions and Answers
How do I properly weld my bung?
If my threads are tight after welding, how do I fix it?
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