Author Topic: Shelf life of SRB's  (Read 524 times)

Offline bknight

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Shelf life of SRB's
« on: April 14, 2022, 09:59:32 AM »
I noticed a member in Cosmoquest ask a question is the SRB' of the SLS perhaps out out of date.  So, what is the shelf-life o them in the humid environment of Florida?
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Offline JayUtah

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Re: Shelf life of SRB's
« Reply #1 on: April 21, 2022, 02:41:21 PM »
Humidity is good for the propellant grains.  They actually have a shorter shelf-life here in Utah because here they dry out and start to crack.  The grain is not very different from a heavy-duty tire.  It looks and feels like sturdy rubber.  And for all intents and purposes, it is.  It's a polyurethane binder.

Humidity wreaks havoc on the steel casing, however.  Especially if it's also exposed to saline sea spray.  The fit tolerances are on the order of 0.030 inch, but corrosion affects the bonding ability of the putty in the field joints.

Non-climate factors affecting shelf life are just pure gravity.  No matter how you store segments, over time gravity pulls them and the propellant grains out of shape.
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Offline bknight

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Re: Shelf life of SRB's
« Reply #2 on: April 23, 2022, 12:16:45 PM »
Humidity is good for the propellant grains.  They actually have a shorter shelf-life here in Utah because here they dry out and start to crack.  The grain is not very different from a heavy-duty tire.  It looks and feels like sturdy rubber.  And for all intents and purposes, it is.  It's a polyurethane binder.

Humidity wreaks havoc on the steel casing, however.  Especially if it's also exposed to saline sea spray.  The fit tolerances are on the order of 0.030 inch, but corrosion affects the bonding ability of the putty in the field joints.

Non-climate factors affecting shelf life are just pure gravity.  No matter how you store segments, over time gravity pulls them and the propellant grains out of shape.

Good information but what approximate timeline does that give for the current SRB of the current SLS assuming they get all the fuel loading issues fixed in a month or so?

Do your buddies at Morton believe the SRB's won't have an issue firing this year?
« Last Edit: April 23, 2022, 12:31:08 PM by bknight »
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Offline JayUtah

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Re: Shelf life of SRB's
« Reply #3 on: April 24, 2022, 11:29:51 AM »
Shouldn't be a problem in any way for an assembled SRB.  It's only the unassembled segments that have to be cared for in a humid environment.  Once they're stacked, all the corrodible surfaces are covered.
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Offline bknight

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Re: Shelf life of SRB's
« Reply #4 on: April 24, 2022, 02:12:18 PM »
Shouldn't be a problem in any way for an assembled SRB.  It's only the unassembled segments that have to be cared for in a humid environment.  Once they're stacked, all the corrodible surfaces are covered.

Cool should the joints/gasket/putty be acceptable ala Challenger (though obviously not cold).
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Offline bknight

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Re: Shelf life of SRB's
« Reply #5 on: April 24, 2022, 03:45:05 PM »
I have another question as I have not been associated with a major governmental project, or any governmental project, such as SLS.  After the rocket is moved back to the VAB and dissected, about how long will the enigineers typically take to make a report?  A month, longer?
« Last Edit: April 24, 2022, 03:46:49 PM by bknight »
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Offline cjameshuff

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Re: Shelf life of SRB's
« Reply #6 on: May 03, 2022, 08:36:33 AM »
Humidity is good for the propellant grains.  They actually have a shorter shelf-life here in Utah because here they dry out and start to crack.  The grain is not very different from a heavy-duty tire.  It looks and feels like sturdy rubber.  And for all intents and purposes, it is.  It's a polyurethane binder.

Humidity wreaks havoc on the steel casing, however.  Especially if it's also exposed to saline sea spray.  The fit tolerances are on the order of 0.030 inch, but corrosion affects the bonding ability of the putty in the field joints.

Non-climate factors affecting shelf life are just pure gravity.  No matter how you store segments, over time gravity pulls them and the propellant grains out of shape.

Polybutadiene, you mean? I'm surprised the hydration level of the grain is allowed to be that high, since it's essentially inert mass, and water doesn't appear to be produced by the curing process. And of course the corrosion issues you mention...an ammonium perchlorate-rich material in a steel pressure vessel seems like a strong argument for minimizing moisture.