Bulkhead + chipped glass question.

[fishguy1978]

If you silicone a piece of glass over the holes it is the fay seal not the fillet that is of concern. Fay is between the two surfaces and fillet is around the edge. I work for a large aircraft manufacturer in the Pacific North West and per our spec if you apply a 0.02in ish ( and I mean ish) thick layer of adhesive and get squeeze out (this is very important) all the way around (absolutely important) then you are good. Use clear glass and clear silicone so that you can see if there are any air bubbles trapped. After fay sealing, you will want to fillet the edges. Where the patch is against the other pane ensure there is adequate silicone to fill the gap and then fillet over that as well. I have 2 glass patches in my 220 gallon tank and this is how I installed them.

 

[Backfromthedead]

I've ran tanks successfully with cracks like that in the holes. Just use some silicone to seal it on both sides.

 

[Sassafras]

fishguy1978's advice sounds logical and based on experience. I don't think any of us have addressed your concern about removing some of the old silicone so that you have a clean glass surface onto which you can bond the new glass "patch". It looks like if you tried to put new glass in place, one edge would be right on top of the old corner seam fillet. Is there any clean glass surface between the hole and the corner seam? I think tying the new glass to both the surface with the holes and the other pane is important for strength where the hole nearly meets the edge of the glass.

 

[fishguy1978]

Sassafras is correct. You will need to remove the fillet from the old seal but only the fillet and limited to double the thickness of your patch on each side of the patch. You will then replace the fillet with new sealant. 250mils = 6mm approximately =.25in approximately so any material that is less than 1/4in the fillet continues over the top edge of the patch material. For materials that are .25 or thicker it does not need to.

 

[Zk92]

Sassafras is correct. You will need to remove the fillet from the old seal but only the fillet and limited to double the thickness of your patch on each side of the patch. You will then replace the fillet with new sealant. 250mils = 6mm approximately =.25in approximately so any material that is less than 1/4in the fillet continues over the top edge of the patch material. For materials that are .25 or thicker it does not need to.View attachment 1479087

Yes, this is exactly what I planned on doing originally.

But, my main question is, is the integrity of the glass effected by that chip if I just use a reversed and capped bulkhead?

I only want to put a piece of glass in as a last resort beings that I have such tight space to work with.

 

[fishguy1978]

Yes, this is exactly what I planned on doing originally.

But, my main question is, is the integrity of the glass effected by that chip if I just use a reversed and capped bulkhead?

I only want to put a piece of glass in as a last resort beings that I have such tight space to work with.

I would be less trusting of a reversed bulkhead. No, I don't think the glass will be significantly weakened by the chip. You can blend the chip with some chrocus cloth or fine grit sandpaper just so that it is smoothed out if you want.

 

[Sassafras]

I can appreciate the difficulty of working with the glass in such a tight space, but it would also be a lot of trouble to replace a bulkhead fitting if it started to seep later on. If it is possible, I would go with the glass. The corner seam would have better integrity with the glass and additional silicone in place than with the bulkhead and less silicone sealant.

 

[Zk92]

I would be less trusting of a reversed bulkhead. No, I don't think the glass will be significantly weakened by the chip. You can blend the chip with some chrocus cloth or fine grit sandpaper just so that it is smoothed out if you want.

What are some concerns with a reversed bulkhead? Sorry, im trying to weigh all my options.

Thank you very, very much for all the information so far, by the way. Thank you everyone.

 

[fishguy1978]

What are some concerns with a reversed bulkhead? Sorry, im trying to weigh all my options.

Thank you very, very much for all the information so far, by the way. Thank you everyone.

It has to do with the original intent of the design. The o-ring is intended to be installed on the wet side. Installing the o-ring on the dry side can lead to a leak.

 

[Sassafras]

My concerns would include the greater likelihood of a future leak, but also the fact that the glass option reinforces the area where the hole is so close to the edge seam. By reinforced, I mean that if the glass patch is properly siliconed both to the pane with the holes and to the adjacent pane, the seam would be strengthened. Not that removing silicone to install the bulkhead would necessarily result in failure of the seam, since it is just fillet material, but it certainly wouldn't do anything to beef up that weak area.