Pressure Sciences is currently performing a feasibility for the U.S. Department of Transportation (DOT), for “Enhanced Protection for MC-331 Cargo Tanks in Frontal Collisions.” In performing this work, we will study methods to improve the crash-worthiness of the front heads of these cargo tank motor vehicles, and suggest appropriate standards for design and construction. Analytical work will involve parametric studies on various scenarios of front end collisions. We will be looking at energy absorption devices, and designs for redirection and diversion of impact energy, with the goal for prevention of front head fracture.

Pressure Sciences has previously qualified for design engineering, approval, and certification of D.O.T. hazardous materials containers. We obtained registration from the U.S.D.O.T. under 49CFR107.503 as a design and approval certification agency in July 1991. Registration was sought from the Office of Hazardous Materials Transportation (OHMT), and approval authority was obtained for Subpart C Cylinders, Subpart D Containers, Subpart H Portable Tanks, and Subpart J Containers for Motor Vehicle Transportation (Specifications MC 200, 201, 331, 338, 406, 407, and 412).

Pressure Sciences is engaged in design and analysis of a variety of pressure vessels, tanks, and piping systems - including cylinders, cargo tanks, and cargo tank motor vehicles. Under the referenced registration, our qualifications include:

• Evaluation of design drawings, design, and stress calculations,
• Knowledge of applicable regulations under Title 49 of the Code of Federal Regulations,
• Ability to conduct, monitor, and evaluate test procedures and results,
• Ability to perform stress analysis of pressure vessels to demonstrate compliance to the applicable DOT specification,
• Registration of staff as Professional Engineers.

An interesting job that Pressure Sciences completed several years ago involved designing a hypergolic fuel (liquid rocket fuel) tanker for NASA.

Pressure Sciences worked with Process Engineering, Inc., who was awarded a contract by EG&G Florida, Inc., for the design of a semi-trailer for the transport of the highly hazardous and toxic hypergolic fuel components (nitrogen tetroxide and mono-methylhydrazine) for NASA. The semi- trailer consisted of inner and outer stainless steel vessels. Crushable, energy-absorbing material was positioned at the front of the trailer, and the sides are strengthened with reinforcing members to protect against breaching of the inner vessel under impact. A unique feature of the support system was the cone that connected the inner vessel to the outer shell. This cone allowed thermal movement in both directions, and provided exceptional bending, tension, and compression strength.

For normal conditions, analyses were performed using finite element models, supplemented by hand calculations to demonstrate detailed compliance with the MC-338 DOT specification. Dynamic analysis performed by imposing a known over-the-road vibration spectrum on the beam model was used to obtain the structural response of the tanker. Then critical components were evaluated for their capability to withstand the resulting fatigue loading.

Accident analyses to demonstrate its capability to withstand a lateral, or “T-Bone,” impact were done by a combination of hand calculations relating to impact and dynamic finite element analyses using the beam model. The tanker was demonstrated to be capable of withstanding a 55 mph frontal impact with a rigid bridge abutment without rupture, and a 55 mph lateral impact by a tractor-trailer combination of the maximum allowable over-the-road weight of 80,000 pounds, also without rupture. It was also shown capable of withstanding immersion in the fire produced by the hypothetical burning of truck diesel fuel following an accident.

Twenty-three of these tankers have now been built: the first two for the Kennedy Space Center and the others for Kelly Air Force Base.

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