PROCESS SAFETY MANAGEMENT -
ENGINEERING SUPPORT
MECHANICAL INTEGRITY OF PROCESS EQUIPMENT
BACKGROUND
Various toxic, reactive, or flammable materials (most often liquids
and gases) have been categorized by the federal government and by some
state agencies as "highly hazardous chemicals". Several major
disasters have occurred in which the unexpected release of hazardous substances
has resulted in damage, injury, and even loss of life. In response to these
disasters, federal and state legislation has been enacted in an effort
to better control processes involving hazardous substances - most notably
by the EPA and OSHA.
The direct approach to controlling releases from processes involving hazardous substances is to assure that these substances are adequately contained within the "pressure boundaries" of the process equipment (e.g., vessels, tanks, and piping). In fact, it is a requirement of both federal and state legislation that the pressure boundaries of such process equipment be protected by implementing proactive plans to assure the structural integrity of new equipment and to maintain the on-going structural integrity of in-service equipment.
To this end, it is incumbent upon the owner/operator to ensure that new process equipment, as fabricated, is suitable for the application for which it will be used. Appropriate checks must be performed to ensure that equipment is installed properly and that the installation is consistent with the design specifications and the manufacturer's instructions. In-service equipment must be periodically examined, tested, and evaluated (condition assessment) to assure that its state of fitness is consistent with its current operational requirements. When maintenance, modification, repair, or replacement is required, the owner/operator must assure that the materials, spare parts, and equipment employed are suitable for the process application (service) in which they will be used. By addressing these issues, the owner/operator assures the total structural integrity of process equipment throughout its useful life.
MECHANICAL INTEGRITY COMPLIANCE
In 1992, OSHA issued regulations in 29 CFR 1910.119 for Process Safety Management of Highly Hazardous Chemicals. Section 1910.119(j) lists the requirements for establishing and maintaining the ongoing mechanical integrity of process equipment -- including pressure vessels, storage tanks, piping, valves, relief & vent systems, emergency shutdown systems, pumps, and controls & interlocks. The capability to assure that clients comply with the technical requirements of this law is a key element of Pressure Sciences' core business. We are often relied upon to help establish Mechanical Integrity programs, perform site Documentation and Inspection (D&I), evaluate, prioritize and qualify plant process equipment, recommend upgrades and redesigns, and certify the integrity of plant pressure components through documented reports from our professional engineering staff.
Our involvement with the OSHA PSM initiative dates from 1984, when Dr. Selz first proposed writing a Process System Safety Standard under the aegis of the ASME. The industry strongly preferred to see guidelines rather than an explicit standard, and these guidelines were later produced by the AIChE Center for Chemical Process Safety and the Chemical Manufacturers Association (CMA). In the interim, we served as reviewers for the first drafts of the OSHA regulations, providing comments to OSHA in 1990.
Pressure Sciences has implemented baseline D&I programs, and performed evaluations of pressure vessels, piping and storage tanks for many manufacturing, chemical and petrochemical process plants to help them comply with the Mechanical Integrity portions of the OSHA Process Safety Management. The work has generally taken the form of:
We have performed projects of this nature for many clients whose operations
fall under the PSM regulations.
MANAGEMENT OF CHANGE
Pressure Sciences is experienced in the development of engineering
and design change control systems, and in performing independent audits
of regulated facilities for implementation of the OSHA 1910.119 standards,
including auditing to the requirements of paragraph (l), Management of
Change. Our most prominent and well-documented job is for the Commonwealth
of Pennsylvania at Koch Hydrocarbon's Schaefferstown (PA) LPG Storage facility
(see project description below), which is performed on an annual basis.
Pressure Sciences was originally engaged to review the safety of the proposed
construction of the two 10 million gallon refrigerated storage facilities
additions, and has been retained since 1993 for the annual audits mandated
by Harrisburg. Management of Change is a primary focus of these audits.
CASE STUDY
For the Commonwealth of Pennsylvania, Pressure Sciences, Inc., performed an independent, third party review of the public and environmental safety of a refrigerated liquefied propane gas (LPG) storage facility. The facility is located in Schaefferstown, near Harrisburg, PA. The review became necessary when local citizens expressed serious concerns about a large addition to the existing Schaefferstown Liquefied Propane Gas Facility.
The original facility contained 21 tanks, each of 30,000 gallons capacity. These tanks are used to store liquid propane at ambient temperature and pressures up to 250 psig. The addition consists of a large refrigerated storage facility that stores liquid propane at -44°F, but at atmospheric pressure. It includes two ten-million gallon storage tanks and the necessary pumps, compressors, condensers, piping, valves, and other ancillary equipment.
Construction in accordance with API 2510 and NFPA 58, Chapter 8 was prescribed by the Commonwealth in granting the client permission to add to its existing facility. Many other codes and standards are referenced by these two documents. The most significant ones are API 620, including Appendix R, Low Pressure Storage Tanks for Refrigerated Products; ANSI/ASME B31.3 for piping design and construction; and API 2510A for guidance on fire protection.
In performing the review, Pressure Sciences addressed the client's design and construction of the addition, plus its planned management of process hazards during plant start-up, operation, inspection, maintenance, and future modification. The addition is tightly integrated into the existing facility, so the entire facility was considered when fire safety and management of process hazards were reviewed. Public and environmental safety were also addressed from the standpoints of system reliability, mechanical integrity, the reliability of the flare system, the reliability of the compression-refrigeration system (including its supply of electric power), and the behavior of propane vapor clouds. In the particular area of fire protection, we recommended, and the client agreed to make very significant improvements.
Management of process hazards was evaluated using OSHA Process Safety Management of Highly Hazardous Chemicals (29 CFR 1910.119). This regulation became law after construction of the Schaefferstown facility addition was begun. Therefore, its use was not originally required by the Commonwealth. Nevertheless, it is an excellent tool for evaluating plant safety and we recommended to the Commonwealth that it be applied to this project. This OSHA regulation addresses, in part, procedures for operation, training, maintenance, management of design change, and other aspects of plant safety not addressed merely by adequate original design and construction.
Dr. Selz testified as to the safety of the modified facility at three separate hearings in Commonwealth Court, presided over by President Judge David Craig. Ultimately, the Court permitted construction of the facility to be completed, and operation to begin.
The OSHA regulation requires periodic evaluation of the facility to ensure that mechanical integrity, training, management of change, and other safety-related elements of construction and operation remain acceptable. Accordingly, Pressure Sciences has continued to evaluate the facility on an annual basis.
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