Aerospace Sourcing
Parts: chemicals

Shelf Life Control: Buying and Receiving Age Sensitive Items

Shelf life control is the set of rules that keeps sealants, adhesives, lubricants and rubber parts from being used after they degrade. The DoD program is DoDM 4140.27, which splits items into Type I (fixed, non extendible) and Type II (extendible after inspection or test), and MIL-STD-129 sets how the dates are marked.

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What shelf life control is and what governs it

A shelf life item, as MIL-STD-129R defines it, is an item of supply with deteriorative or unstable characteristics to the degree that a storage time period is assigned so it will perform in service. Shelf life runs from the date of manufacture, cure, assembly, pack or, for some frozen items, shipment, and ends at the date the item must be put into service or inspected, tested or restored. It is not the same as service life.

The DoD program sits in DoD Manual 4140.27, DoD Shelf-Life Management Program, in two volumes: Volume 1, Program Administration, and Volume 2, Materiel Quality Control Storage Standards. We could not open the manual itself when writing this page, so the definitions below are quoted from MIL-STD-129R with Change 2 (27 September 2019), the marking standard that implements them. Commercial programs usually follow the same logic through their own material specs and the industry documents named below.

DocumentRoleStatus as checked
DoDM 4140.27, Vol 1 and 2DoD shelf life program administration and storage standardsCited by MIL-STD-129R; not read directly
MIL-STD-129RMilitary marking for shipment and storage, including shelf life marking and shelf life codesChange 2, 27 September 2019
MIL-HDBK-695ERubber products: recommended shelf life, guidance onlyDated 20 October 2011
MIL-STD-1523AAge controls of age sensitive elastomeric materialCancelled. Notice 2 (16 November 1999) points hose to SAE AS1933 and seals to SAE ARP5316.
SAE ARP5316Storage of aerospace elastomeric seals and seal assemblies before hardware assemblyDoD adopted, per MIL-HDBK-695E
SAE AS1933Age controls for hose containing age sensitive elastomeric materialDoD adopted, per MIL-HDBK-695E
SAE AS5502Standard requirements for aerospace sealants and adhesion promotersCited by MIL-STD-129R for sealant dating

Type I and Type II shelf life

The type decides what happens when the date arrives. A Type I item is thrown away; a Type II item can be tested and extended.

Type IType II
Definition (MIL-STD-129R)A definite, non extendible period of shelf life, set from technical test data or experienceAn assigned period that may be extended after visual inspection, certified laboratory test or restorative action
Date markedExpiration date: the date by which the item is discarded as no longer suitable for issue or useInspect/test date: the date by which the item is inspected, tested or restored
Shelf life codeAlpha codes, excluding XNumeric codes and X
After extensionNot extendible (Type I medical items in the DoD/FDA program are the stated exception)Extended material gets a DD Form 2477, Shelf-Life Extension Notice, before issue or shipment

A shelf life code of zero means non deteriorative, and those items need no shelf life marking. The shelf life code itself identifies both the number of months of original shelf life and whether it is Type I or Type II. MIL-STD-129R Table IV also sets how many months or quarters must remain when material is received by the first government activity, which is the number to copy into a PO when you buy for a government contract.

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How the dates are written, including cure dates for elastomers

Rubber is dated by cure, everything else by manufacture. MIL-STD-129R defines the cured date as the date the material was altered industrially, as to vulcanize rubber or treat synthetic elastomers with heat or chemicals to make them infusible, and allows a cured date only for elastomeric and rubber products.

  • Non cure dated items are marked by numeric month and the last two digits of the year, with the day taken as the last day of that month. Example from the standard: MFD DATE 10/13, EXP DATE 10/14 for a Type I item.
  • Cure dated items are marked by calendar quarter and two digit year, with the day taken as the last day of the quarter. Example from the standard: CURED DATE 4Q13, INSP/TEST DATE 4Q18.
  • The words TYPE I or TYPE II are not part of the marking.
  • When unit packs with different dates are consolidated in one container, the earliest dates go on the outer container.

MIL-HDBK-695E gives the same logic for rubber: cure date by month and year where shelf life is up to 3 years, and by quarter and year, for example 2Q-83, where it exceeds 3 years. It also recommends that procurement documents require the cure date to be mold marked on the product or its package. For how this applies to seals, see O-rings.

How long rubber lasts on the shelf

MIL-HDBK-695E Table I groups rubbers by age resistance, using SAE ARP5316 as its basis: silicone, fluorosilicone, polysulfide, fluorocarbon (FKM), perfluorocarbon, butyl and EPDM in the 20 years minimum group; nitrile, neoprene and chlorosulfonated polyethylene at 15 years maximum; urethanes at 5 years maximum; and natural rubber, synthetic polyisoprene and SBR at 3 years maximum. The handbook is guidance only, and the item specification governs where they conflict.

Freezer and refrigerated storage

Cold stored materials add a second control on top of the date: the temperature history. Premixed sealants and film adhesives are the usual examples.

  • MIL-STD-129R recognizes that for select Federal Supply Group 80 items industry batch produces and freezes material to prevent degradation, and that for those items shelf life starts at the date of shipment, which the manufacturer or authorized distributor must guarantee.
  • MMM-A-132B requires structural adhesive containers to carry the date of manufacture by month and year, not by code, an expiration date and a maximum storage temperature, and says film adhesives shall be expedited to cold storage.
  • Rubber storage guidance in MIL-HDBK-695E: below 100 °F, below 75 percent relative humidity, away from ozone sources such as high voltage equipment, out of direct sunlight and ultraviolet light, and issued first in, first out by cure date.
  • Fluids have their own limits; MIL-PRF-83282D notes its hydraulic fluid may be stored from -40 to +50 °C.

For cold chain items, put the shipping condition on the PO (dry ice or coolant, temperature indicator) and keep the receiving record with the lot. The adhesive specifics are on structural adhesives and the sealant specifics on aerospace sealants.

Certificates of analysis and batch traceability

A certificate of conformance says the material meets the spec. A certificate of analysis, or the manufacturer's test report, shows the measured results for that batch. For shelf life items you usually want both, tied to the batch number on the container.

The specs define what a batch is. MIL-PRF-83282D defines a bulk lot as a homogeneous quantity in one container or made in a single plant run not exceeding 24 hours with no change in ingredients. MIL-PRF-81733D requires every sealant component container to be marked with the date of manufacture and the date of packaging. MIL-PRF-23699G lists submittal of conformance test results as something an acquirer can require. If the certificate cannot be traced to a batch number printed on the container, the dates on the label cannot be trusted either. More on cert content is on certificates of conformance and material certs and traceability.

What to put on the PO for shelf life items

  • Full specification, revision and designation (type, class, grade, dash number), plus the qualified product where a QPL applies.
  • Shelf life type and code if it is a government item, or the manufacturer's shelf life if commercial.
  • Minimum remaining shelf life at receipt, in months or quarters. For government contracts, use the MIL-STD-129R Table IV value for the item's code.
  • Required dates on each unit: date of manufacture or cure date, and expiration or inspect/test date, marked per MIL-STD-129 where the contract invokes it.
  • Cure date by quarter for elastomer parts, mold marked or on the package.
  • Manufacturer and batch number on every unit, with a certificate of conformance and, where needed, the batch test report.
  • Storage and shipping condition: frozen, refrigerated or ambient, with temperature indicators for cold chain items.
  • Factory sealed packaging only, no repacking or decanting, and individual packaging for rubber parts as MIL-HDBK-695E recommends.
  • Whether extended Type II material is acceptable, and if so, that it must carry the DD Form 2477 extension notice.

Combining these lines with the rest of the RFQ is covered on the RFQ checklist.

Receiving inspection for shelf life items

Receiving has three jobs: confirm the item, confirm the dates, and confirm the storage history.

  1. Match part or product, spec, designation, manufacturer and batch to the PO and certificate.
  2. Read the dates and compute remaining life against the PO minimum. Check that cure dates on rubber are in quarter format and that the outer container shows the earliest date of its contents.
  3. For cold items, check the coolant and temperature indicator before signing for the shipment, and move the material to storage before paperwork.
  4. For extended Type II material, check for the DD Form 2477 and the test record behind it.
  5. Log the item into a stock system that issues first in, first out by date, and flag it before it expires.

Our general receiving method is on receiving inspection.

Counterfeit and quality risks specific to shelf life items

Shelf life is an easy thing to fake, because the material often looks fine after its date. Watch for relabeled or over labeled dates, labels applied by someone other than the manufacturer, extended material without an extension notice or test record, repacked or decanted product, rubber parts in bulk bags with no cure date, and cold chain items that arrive warm. Each of these breaks the link between the container and the manufacturer's batch. Treat them as nonconforming until traced. Our controls are described on counterfeit parts avoidance.

How we source shelf life items

We do not hold inventory, so nothing we deliver has been aging on our shelf. We source sealants, adhesives, lubricants and elastomer parts through authorized distributors or the manufacturer, put your minimum remaining shelf life, dating and storage requirements on the order, specify the cold chain for frozen and refrigerated items, and check batch, dates and certificates before shipment. We can combine shelf life items with the hardware they go into on one PO, or kit them by build so each kit carries its own dates. For old callouts and discontinued materials we use our obsolete parts process and bring any substitute to your engineering.

Related pages: greases and lubricants and the chemicals category.

Get shelf life items sourced with dates you can use

Send the item list, quantities, the minimum remaining shelf life you need and any cold chain requirement. A person replies within one business day with a source and the paperwork you will receive. Request a quote for shelf life items and hardware. Back to all parts.

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Questions

What is the difference between Type I and Type II shelf life?

Under the DoD program, as defined in MIL-STD-129R, a Type I item has a definite, non extendible shelf life and is marked with an expiration date, after which it is discarded. A Type II item has an assigned shelf life that may be extended after visual inspection, certified laboratory test or restorative action, and is marked with an inspect/test date. Type I items get alpha shelf life codes and Type II items numeric codes or X.

How is a cure date written on rubber parts?

MIL-STD-129R marks cure dated items by calendar quarter and two digit year, for example CURED DATE 4Q13, with the day taken as the last day of the quarter. MIL-HDBK-695E uses month and year for rubber with a shelf life of up to 3 years and quarter and year beyond that. It also recommends that procurement documents require the cure date to be mold marked on the part or its package.

What replaced MIL-STD-1523 for elastomer age control?

MIL-STD-1523A was cancelled. Notice 2, dated 16 November 1999, directs future acquisitions to SAE AS1933, Age Controls for Hose Containing Age Sensitive Elastomeric Material, for hose, and to SAE ARP5316, Storage of Aerospace Elastomeric Seals and Seal Assemblies, for seals. MIL-HDBK-695E lists both as DoD adopted and uses ARP5316 as the basis for its shelf life table.

When does shelf life start for frozen sealants and adhesives?

For select Federal Supply Group 80 items that industry batch produces and freezes, MIL-STD-129R says shelf life starts at the date of shipment, regardless of the date of manufacture, and the manufacturer or authorized distributor must guarantee the required shelf life from that date. Check your contract and the manufacturer's data, and require the cold chain on the PO so the guarantee holds.

How much shelf life should remain when material arrives?

Set a minimum on the PO. For government items, MIL-STD-129R Table IV gives the months or quarters that must remain on receipt by the first government activity for each shelf life code. For commercial programs, base it on how long the material will sit before use, plus margin for receiving and kitting. Without a stated minimum, a supplier can ship material that is days from expiring.

Can expired shelf life material be used?

Type I material cannot be extended and is discarded at its expiration date, with Type I medical items in the DoD/FDA extension program as the stated exception. Type II material can be inspected, tested or restored and given a new inspect/test date, and MIL-STD-129R requires a DD Form 2477 extension notice on extended material before issue or shipment. Commercial programs follow their own material specs and the manufacturer's guidance.

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