Marine Applications: U.S. 30 inch flexible hose limit

[SandCounter]

I considered inquiring in the Marine Engineering sub-forum, but the piping sub-forum sees more interaction.

I am working a project that requires portable machinery installed on the weather deck of a ship. The machinery processes water and returns the water to the ship. The unit will be moved between vessels with each vessel having pre-installed connections from the vessel system for connecting to the processing unit. Nonmetallic, flexible hoses between the portable unit and the water connections on the ship would be the most convenient method for plumbing this portable machinery temporarily over multiple installs on multiple vessels.

I have had a regulator point out that U.S. CFR 56.60-25 prohibits flexible hoses longer than of 30 inches.

There is no increased chance of down flooding, nor is there any notable environment concerns related to a failure that would result in a spill, and likelihood of injury can be easily mitigated both mechanically and operationally. I have seen nonmetallic flexible hoses used in other water applications on the deck of marine vessels, e.g. dredges.

If someone has experience in nonflexible hoses on the deck of a marine vessel, I would like to ask if you could point me in the right direction of an exception to this rule that you might have used to satisfy regulators.

Thanks in advance for the help.

 

[1503-44]

30 inch diameter?

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[SandCounter]

Sorry ax1e, might not have been clear, 30 inches long.

 

[miningman]

Four hoses end to end would give 10 feet, or any other length with enough 30 inch lengths

 

[SandCounter]

I like how you think miningman.

 

[itsmoked]

That seems like such a limiting, case specific, restriction that I'd bet the guy quoting you is misquoting it. Have you actually read the CFR yourself? Checked the exceptions?

Ship fueling lines are certainly longer than 30 inches long. How is your temporary 'service' activity any different than fueling other than it's flowing non-flammable water.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[KevinNZ]

(3) Nonmetallic flexible hose may be
used for plastic pipe in [highlight #FCE94F]non-vital fresh
and salt water systems[/highlight] and non-vital
pneumatic systems, subject to the limits
of paragraphs (a)(1) through (4) of
this section. Unreinforced hoses are
limited to a maximum service pressure
of 345 kPa (50 psi); reinforced hoses are
limited to a maximum service pressure
of 1,034 kPa (150 psi).

(2) Nonmetallic flexible hose may be
used in [highlight #FCE94F]vital[/highlight] fresh and salt water systems
at a maximum service pressure of
1,034 kPa (150 psi). Nonmetallic flexible
hose may be used in [highlight #FCE94F]lengths not exceeding
76 cm (30 inches)[/highlight] where flexibility
is required, subject to the limits
in paragraphs (a)(1) through (4) of this
section. Nonmetallic flexible hose may
be used for plastic pipe in duplicate installations
in accordance with this
paragraph (b).

 

[hydtools]

Use wire-braided hose. Would it be considered metallic and therefore length restriction of non-metallic hose would not apply?

Ted

 

[1503-44]

Get rid of the plastic hose. Problem solved.

Reading between the lines of CFR 56.60-25, it is apparent that plastic hoses are not really a suitable choice. I doubt stringing 30" sections together will be acceptable, as many potential leak points are created at each joint, plus it is obvious the designer was intentionally subverting the regulation. What's inside the hose may not matter to a zero discharge requirement.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[SandCounter]

itsmoked, yes, I have read the regulation. I agree on the ship's fuelling lines. If use of those kinds of hoses are specifically called out as an exception somewhere, that would help my case.

Thanks KevinNZ, that's the regulation alright.

Thanks hydtools, I was hoping not to go there. I could see wire braided hoses getting kinked and incurring mechanical damage over multiple installs/uninstalls. Further I am looking at up to 4" diameter hose which could get very pricy for length and frequent replacement. But, it is an option to consider.

ax1e, looking at the full reg., there is a delineation between plastic pipe and non-metallic flexible hose. Where it says non-metallic flexible hose is used as (I read used in the place of) plastic pipe, it must comply with the requirements of the plastic pipe section.

 

[1503-44]

Fine, then in that case nonmetalic, or even metalic hose, or any substitute would have to comply with the 30" length limit. Or no?

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[SandCounter]

ax1e, as far as I can tell, metallic hose is OK, or at least not addressed.

 

[1503-44]

I think you should try that one .

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[gerhardl]

Hi SandCounter,

I suggest you take a look at flexible hoses offered for offshore installations.

One large manufacturor is Trelleborg, supplying rubber-based flexible pipes world-wide from Norway and Sweden, up to (at least) 40 inch, and also customized solutions

Competitors will surely excist. An experienced producer might be able to give suggestions for suitable solutions not considered yet, and might also have experiene with your type of problems.

As often you can possibly solve an engineering problem with 'an open end' research of what is available on the merket.

Good luck!

 

[SPDL310]

I think the major contention that you would have is if your system is considered a vital or non-vital system. The 30 inch limit only exists for a vital fresh or saltwater system system. The 30 inch limit is seems to be imposed to specifically prevent vital systems from being piped with non-metallic flexible hose except where additional flexibility is specifically required. The 30" limitation is not imposed on a non-vital system. I would look into what the CFR defines as a vital system. I would assume that vital probably means a system that is critical to the safe operation of the ship and crew. The fact that your system is for processing water may qualify as non-vital, as it is not required for safe operation of the vessel. The very fact that it is not required by the original vessel design may classify it as non-vital. Other than cost savings on supply boat runs to remove waste/resupply water there is no reason your system is required for the vessel to operate safely. I would argue that this should should then fall under the same rules as the supply boat water line.

 

[SandCounter]

Thanks for the input SPLD310. It is a vital system as defined by the CFRs. The treatment plant, while not part of the original, approved system is now required by retroactive international regulation. As an alternative, I am looking at manageable pipe spools with victaulic couplings. Could you elaborate on your comment “I would argue that this should should then fall under the same rules as the supply boat water line.”?




Gerhardl, thanks for the tip, I will check cross-industry applications.

 

[SPDL310]

I am not antiquated with the CFR in any way, but have worked on boats offshore platforms etc. in the GOM. There supply boats with large potable water and fuel tanks transport fuel and water to oil rigs, barges and dive barges. The offloading is always done with a 100+ ft hose. Conceptually speaking I don't see your water system performing a different function. You are resupplying a vessel with potable water. The only difference is that you are filtering and purifying the waste water of the vessel instead of pumping it out of a tank. You could search for the exemption that allows this or alternatively you could use a suitable length of metallic flexible hose which is exempt from the length restriction. I don't know how often the unit would be removed but a single flex hose of any variety seems like it would be the preferred option for connection to the vessel as opposed to making an breaking multiple victaulic connections even at twice the price.