Broken Straps on Fresh water tank??

[boom301]

Have a 50 gallon tank in the back of trailer. End of May, while filling, heard a very loud bang. I use a water meter to monitor how many gallons i put in. 200 miles away from home. Right at 49 gallons heard the bang. waited a few, no leaks, underbelly not swollen so i continued camping. Used the tank 2 more times but only 10 gallons at a time. I didnt have time to get under and look. Finally got under it this month and saw these 3 straps, one side sitting on the plastic. 3 broken screw heads and somehow 3 screws just bouncin around. Photos show each strap hanging. The screw heads look like they came from the screws above where the straps lay. Like screwed from top thru strap and then frame. but don't know how the straps came down. Looking at them screws i dont know how they thought they would hold 425+lbs of water, especially while towing. I'm thinking the bang was tank expansion. I don't believe all 3 straps broke simultaneously and the tank is still in place. I plan on bracing from side to side outside of plastic with 2 aluminum or steel channels or something. On long distance travels we usually have about 10-15 gallons in fresh tank and then fill at destination. I read somewhere that these straps really are there for initial install of tank. Im almost believing that since tank is still in place. just has a sag in the middle. Any opinion is welcome

[persistent]

Screw failure at the head end is typical for cheap screws. Some fail when new and are first being installed. Some fail due to corrosion next to the head.

Replace screws with stainless steel if you can find them. Straps should do the job just fine. U-channel or angle beam can work but are over kill.

I wish you good luck and happy trails ahead.

[boom301]

They are screwed in from the top. the tank is held in place by frame. Tank sits on screw heads.

[persistent]

A strap under load puts shear force on the screws. That force is at the point the screw shaft joins the head. That is the weak point for hydrogen embritlement, salt water corrosion, or other corrosion process. Heads break off.

Hydrogen embritlement is in the steel chemistry. The process used for making cheap screws may not be well controlled. Heads break off.

Environmental corrosion can be reduced by sealing the steel screw. A chromate primer with an enamel finish coat will probably do the trick.

Stainless steel is resistant to these failure modes.

[franktafl]

Lowes has stainless steel screws and bolts. But you need to be careful since stainless can be brittle.