# In house external pressure testing **URL:** \ **Category:** General Discussion\ **Created:** [May 27, 2022, 2:30pm UTC](https://discuss.bluerobotics.com/t/in-house-external-pressure-testing/12214 "2022-05-27T14:30:53Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![model14](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@model14](https://discuss.bluerobotics.com/u/model14)\ **Post date:** [May 27, 2022, 2:30pm UTC](https://discuss.bluerobotics.com/t/in-house-external-pressure-testing/12214/1 "2022-05-27T14:30:53Z")
Do you have a means of water pressure depth testing for 4" x 12" WTE’s at your facility? A hydrostatic test chamber. ---
**Author:** ![EliotBR](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/eliotbr/32/6937_2.png) [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)\ **Post date:** [May 30, 2022, 12:05am UTC](https://discuss.bluerobotics.com/t/in-house-external-pressure-testing/12214/2 "2022-05-30T00:05:46Z")
Hi @model14, I asked about this internally and apparently we do have the capability to test enclosures of that size at one of our facilities, but > [@BrianBR](#): > > Testing big enclosures is a little tricky. The risk of dangerous/damaging implosions means we typically avoid it. > … > technically we can fit [a 4" x 12" WTE] but we probably wouldn’t want to take it near failure. > > I hear there are ways to reduce damage from implosion by filling the internal volume with something like plastic beads. * * * If you’re looking to test something of your own, note that we usually don’t have available capacity to run tests for uses outside the company. The [Under Pressure](https://bluerobotics.com/learn/under-pressure/) pressure vessel design software may be helpful for at least determining a theoretical pressure limit 🙂 ---
**Author:** ![model14](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@model14](https://discuss.bluerobotics.com/u/model14)\ **Post date:** [May 30, 2022, 1:56am UTC](https://discuss.bluerobotics.com/t/in-house-external-pressure-testing/12214/3 "2022-05-30T01:56:05Z")
When your specs say a 4" tube is rated to 150m, is this based on calculations or empirical data? ---
**Author:** ![EliotBR](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/eliotbr/32/6937_2.png) [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)\ **Post date:** [May 30, 2022, 5:34am UTC](https://discuss.bluerobotics.com/t/in-house-external-pressure-testing/12214/4 "2022-05-30T05:34:03Z")
Both. Calculations give a theoretical maximum depth limit, and pressure tests can be either “to failure” (which we’re more likely to do in open water, for safety reasons) to give a tighter maximum limit, or “to success” to give a weaker bound on what is at least confirmed to work for a given sample. Any rating is statistical (i.e. even if we pressure tested every component that goes out the door it could in principle fail on a future pressure cycle, not least because materials and components degrade over time / with use), but our ratings are provided from at minimum a theoretical calculation and an indicative test of a similar/representative component (e.g. enclosure tubes with the same material, diameter, and wall thickness tend to behave predictably across similar lengths). Depending on the confidence we want and/or how close we want to push a component to its theoretical limit we may do a variety of additional tests (e.g. higher sample numbers, and/or system tests in conjunction with several other components) before deciding on a rating. I would note that our testing capabilities are continually improving, and occasionally after additional testing a rating may change, which is then reflected in the Revision History section in the Technical Details of the relevant product(s). As a couple of examples: > [@Lumen Subsea Light for ROV/AUV - Technical Details - Revision History](#): > > ### 16 December 2019 > > - Depth rating decreased from 950m to 500m based on follow-on pressure testing > [@Ping Sonar Altimeter and Echosounder - Technical Details - Revision History](#): > > ### 23 July 2021 > > - Typical usable range value extended from 30m to 50m based on follow-on usage and variability testing ---
**Author:** ![model14](https://avatars.discourse-cdn.com/v4/letter/m/eb9ed0/32.png) [@model14](https://discuss.bluerobotics.com/u/model14)\ **Post date:** [May 30, 2022, 12:00pm UTC](https://discuss.bluerobotics.com/t/in-house-external-pressure-testing/12214/5 "2022-05-30T12:00:18Z")
Very informative, thank you.