Physical Testing

CAD Design
Fatigue and Fracture Analysis
Damage Tolerance
Stress Analysis
Finite Element Analysis
FTP Portal Module
3-D CAD Images


Trailers of All Types

DOT MC 331, 338, 406, 407, 412 CARGO TRAILERS

LPG, NH3, CO2, Chlorine and cryogenic transports; complete design and stress analysis.

  • HLA  is a Design Certifying Engineer for the DOT (Registration Number CT-0012), with over 21 years of experience in the design and analysis of DOT MC equipment: cargo transport trailers of all types and DOT 51 containers - both portable and intermodal. HLA has designed LPG & Anhydrous Ammonia Cargo Trailers (10,500 - 17,000 W.G.), Chlorine, CO2, SO2 and Cryogenic Transport Trailers.


  • HLA completed a contract for the DOT in January of 1985, to determine the stresses in the head to shell joint of typical MC331 vessels. This stress study centered on the Rub Plate Box area of the typical MC331 cargo transport. The resulting surface stresses were compared to present DOT code allowables, demonstrating the need for revised MC331 structural integrity guidelines. Plumbing guards, bumper and design acceleration inconsistencies were also pointed out in the report.


  • HLA played a significant role in the redefinition of the over-the-road design acceleration requirements for MC331 vehicles. In communication with the DOT, HLA pointed out the need to correct the "Principal Stress Equation", then called "DOT Effective Stress", and was largely responsible for the correction in CFR49.


  • HLA has worked on many difficult topics in the MC 306, 307 & 312 areas: non-linear (plastic) bumper analysis, non-linear roll-over guard analysis with resulting shell stresses, as well as stiffener ring and baffle location and geometry to coordinate with roll-over protection.


  • HLA has over 21 years of experience on the design and analysis of ASME Pressure Vessels, Divisions 1 and 2, API 620 and 650: horizontal, vertical and spherical, including saddles, skirts, columns and other support systems. HLA has designed and analyzed numerous pressure vessels to ASME Pressure Vessel Code, Section VIII, Division 1 requirements. Several subcontracts for NASA projects involved the design and analysis of cryogenic vessels for use in the rocket program. These vessels were designed and analyzed to ASME Pressure Vessel Code, Division 2, with the resulting analysis submitted to NASA for review. This analysis also utilizes the finite element analytical technique for not only the pressure and dead loading, but for seismic and wind loads.


  • HLA performed an extensive damage tolerance study of dry cargo containers for the Institute of International Container Lessors (IICL), which was over five years in length. A survey was made of various types of construction of existing dry cargo containers, and a series of physical tests in combination with finite element computer modeling was used to determine the types of damage, extent and location of damage these containers can tolerate without being repaired.


  • HLA has designed, tested and received ABS approval for more than 11 different designs of intermodal dry cargo and tank containers, including military containers with end and side doors, and refers.

National Propane Gas Association

A major transportation project was performed by HLA for the National Propane Gas Association. HLA Engineers had a contract to perform a study of the Department of Transportation (DOT) regulations governing the design of MC331 transport trailers - making recommendations of design accelerations and stress criteria changes to the regulations, based on stress analyses of existing equipment designs, details and practices. The end result is intended to be a concise guide for the design engineer, and will hopefully assist him in making consistent, safer decisions for the design of this type of transportation equipment.

HLA has also performed design and analysis of ASME pressure vessels (Section VIII, Divisions 1 and 2), cryogenic pressure vessels, ISO intermodal tank and dry cargo containers, MC 331 transports and many other types of transportation equipment.

  HLA Engineers, Inc.
7267 Envoy Court
Dallas, Tx. 75247
Office: 214-267-0930
Fax :     214-267-0970
Email :

 ©2007 HLA. All Rights Reserved  Privacy Policy | Legal Statement | Home | About Us  Specialties | Projects | Contact Us | Job Opportunities | Management | Site Map