MIL-STD-810 Rail Impact
Military rail shock and impact testing is to test material, transported by rail, and determine the effect of impacts during shipment. MIL-810 rail impact testing is used to verify the structural integrity of the material. It also works to evaluate the adequacy of the tiedown system and the tiedown procedures. And it is used to assess transportability in accordance with Military Surface Deployment and Distribution Command Transportation Engineering Agency (SDDCTEA) policy.
This method replicates the railroad car impact conditions that occur during transport of material. As well as the tiedown arrangements of the specified logistic conditions. This Method is based on the Association of American Railroads (AAR) Open Top Loading Rules’ commercial rail transport requirements.
All items are to be tested at their maximum gross weight rating, unless otherwise specified. The number of railroad car impacts that occur in the life of the material may exceed the number recommended here. It is unlikely that impacts at or above 12.9 km/h (8 mph) will occur more often than those defined here.
The following information is extremely technical in nature. It provides a summary of test method 526.2 as derived from the MIL-STD 810 rail impact section. Even though the language is from MIL-STD 810H rail impact, it applies previous versions of the standard. This includes MIL-STD 810G rail impact.
What are the Limitations of Military Rail Impact Testing?
This method is not intended for railcar crash conditions. Nor is it for testing small, individually packaged pieces of material shipped on a pallet, or as part of larger material. All developed loads consisting of ammunition and explosive items must be reviewed and approved by the appropriate approval authority.
In What Ways Can This Test Method Be Tailored for Best Rail Impact Testing?
This method is tailorable only for cargo requiring extraordinary attention, e.g., one-of-a-kind, high value, or key military material. Any changes to the test procedure and criteria must be approved by the Director of SDDCTEA.
What is the Correct Sequence for this Test?
Use the anticipated life cycle sequence of events as a general sequence guide. Sequencing among other methods will depend upon the type of testing (developmental, qualification, endurance, etc.). As well as on the general availability of test items for test.
Normally, shock tests are scheduled early in the test sequence, but after any vibration tests. The order of the rail impact testing will be determined by the requesting organization. Specific sequential test requirements should be stated in the test plan.
What Ought to Be Considered In Determining The Best Test Sequence for Your Material?
- Sometimes the rail impact environment is deemed particularly severe. The chances of material survival without major structural or functional failure are small. In such cases rail impact tests should be first in the test sequence. This provides the opportunity to redesign the material to meet the rail impact requirement before testing to the more benign environments.
- Occasionally, the rail impact environment is deemed severe but the chances of the material survival is good. In such cases, perform the shock test after vibration and thermal tests. This allows the stressing of the test item prior to rail impact testing to uncover vibration, temperature, and shock environmental failures.
- In some cases the rail impact environment could damage joints or seals, or affect Electromagnetic behavior. Here, perform the rail impact test before Electromagnetic Environmental Effects Testing.
- There are often advantages to applying rail impact tests before climatic tests, provided this sequence represents realistic service conditions. Test experience has shown that climate-sensitive defects often show up more clearly after the application of the rail impact environment. However, internal or external thermal stresses may permanently weaken material resistance to vibration and rail impact. This may go undetected if shock tests are applied before climatic tests.
What are the Effects of this Military Impact Test?
Rail impact shock has the potential for producing adverse effects on the physical and functional integrity of transported material. The following are examples of problems/failures that could occur:
- Loosening of restraints
- Failure of attachments, creating a safety hazard
- Shifting of material on the railcar
- Failure of material
- Structural failure
- Fuel spills
What is the Appropriate Process for Military Rail Testing?
All 810 impact testing should be performed in a rail impact testing lab. Keystone Compliance is a military impact lab with significant 810G impact and 810H impact experience. Our test engineers have in-depth knowledge to assure rail impact certification for your product. The following are requirements for performance of the basic rail impact test.
- Buffer Railcars:
- Loaded cars are preferred for use as the buffer or struck cars; empty cars may also be used. In either case, the total weight of the buffer cars must be at least 113,400 kg (250,000 lb). The first buffer car must be a standard draft gear car. The remaining buffer cars should have standard draft gear, if possible.
- The AAR conducts ‘field rail impact tests’ at locations other than DoD test centers. For these ‘field rail impact tests’, unloaded buffer cars may be preferred. This is so that the loads on/in the available buffer cars are not damaged during the impacts. The SDDCTEA needs to approve the use of loaded cars for a ‘field rail impact test’.
- Test Railcar:
- Test railcars must be equipped with chain tie-downs and end-of-car cushioned draft gear. Other railcar types may be approved by the Director of SDDCTEA. SDDCTEA is the designated DoD agent for land transportation. Some material may require other types of railcars for testing to be representative of the intended shipping methods.
- At least one locomotive or railcar mover capable of moving the railcars up to the required impact speeds. If a locomotive or railcar movers is not available use an inclined tangent track.
- A minimum 61 m (200 ft) length of dry, level, tangent track is required between the buffer cars and test car. This allows acceleration of locomotive and test car to specified impact speeds.
What Controls are used for the Rail Impact Compliance Test Process?
Load and secure the test item as would be done for actual rail transport. All contact areas of the test item railcar, lading, and securement items must be free of ice, snow and debris. The tie-down provisions shall provide the entire restraint of the test item.
Sometimes use of a test item representative of the secondary load is precluded. In such cases, use a substitute item equal in weight and similar dynamic characteristics to. Prior to using a substitute test item, obtain approval from SDDCTEA.
For wheeled vehicles, tires must be inflated as uniformly as possible to the tire manufacturer’s recommended highway pressures.
Trailers should be tested both connected to and disconnected from their prime mover. That is unless otherwise specified in the detailed test plan and approved by SDDCTEA. Secure the trailer to the railcar with the lunette resting on the deck. Or secure it with landing legs extended, or tested as a Trailer-On-Flatcar (TOFC).
Lumber or hardware that are not a Basic Issue Item (BII) for the trailer may not be added. This prohibits the use of wooden stanchions.
For vehicle fuel tanks, ensure all fuel tanks for test items are approximately 3/4 full during the test. Unless otherwise specified, fuel and other bulk liquid tankers should be tested at both 60 percent full and fully loaded conditions.
The maximum sloshing force is generated when the liquid fill percentage is close to 60 percent. If it is desired, or there is a need, to use a substitute for fuel (i.e. HAZMAT concerns), contact SDDCTEA for approval.
Vehicles may be equipped with either variable height or pneumatic suspensions. Variable height suspensions must be lowered into transport mode. Pneumatic suspensions must be bled prior to securing the vehicle to the railcar. This is so the vehicle is resting on hard stops.
If applicable, all manually inserted suspension stops must be inserted and secured. This prevents air suspensions from leaking and losing pressure. Leaking causes the vehicle to lower significantly in transit and introduce an unsafe amount of chain slack.
What Shock Laboratory Should You Trust?
Looking for the best rail impact lab for your product’s compliance certification testing? Keystone Compliance experts understand the requirements of military impact testing. They are knowledgeable about MIL-810G rail impact and Mil-810H rail impact. Talk to our experts to develop a streamlined test plan and receive a professional and affordable quote.
Keystone is a certified military rail testing lab, recognized as one of the best rail impact laboratories in the country. Our capabilities include testing to commercial and military standards. Contact us to learn why so many manufacturers rely on Keystone Compliance’s testing services.
There have been several versions of rail impact testing procedures in MIL-STD-810 rail impact testing. Below is a list of each version and the appropriate method number: