The Environmental Protection Agency (EPA) mandates limits of benzene emissions while loading ships, barges, tank trucks and railroad tank cars throughout the United States. EPA does not specifically state that its rules apply to vessels, but rather to a facility which loads a minimum of 1,300 cubic meters per year of a cargo which is at least 70 percent benzene. In practice, every marine facility which loads a ship will load at least that much cargo, and it must be loaded into a tank which is sufficiently vapor tight. To verify tightness, the facility must have either a certificate from a vessel or conduct a tightness test on the vessel. Tightness testing can be accomplished by any of the following: 1. Loading while pulling a vacuum on the vessel's tanks. This is really an operational requirement, not a test. 2. Testing of the tightness during loading using "test method 21," which uses a hand-held gas detector calibrated to compensate for background concentrations of vapors. Described in 40 CFR part 60, this test for leakage must be con ducted either during the last 20 percent of the loading, or have been conducted during the last 20 percent of a loading within the preceding 12 months. 3. Testing the tightness of tanks with air or inert gas at 1.0 psi (gauge). By requiring that all vessels be tight, EPA hopes to achieve a 98 percent reduction in the emissions from tank vessel loadings. These rules were enforceable as of July 23, 1991, however, a number of interpretations will be needed to clarify their intentions before they can be fully carried out. Since the facilities enforce the rules, a ship operator or agent should address any questions to the loading facility. EPA anticipated one difficulty in the implementation of its rules. According to test method 21, when a vessel is tested for benzene leaks at the 80 percent (or more) full level and does not meet the test standards, it either must be repaired before its next loading or must provide documentation that it cannot feasibly be repaired without dry-docking. In the latter case, the vessel may continue to load benzene until that dry-docking. Safety regulations Although it is EPA and not the Coast Guard which requires vapor recovery for benzene, the recovery arrangements might be fraught with safety hazards without a vapor emission control system. To achieve safe operating conditions with a new technology, the Coast Guard strives for a ten-fold increase in safety. However compliance is achieved, a vessel must contain benzene vapors in order to return them to shore. In doing so, there are three areas of concern. 1. Keeping cargo tank pressure within allowable limits. 2. Preventing overfill of the tank. 3. Protecting the vessel from a fire or explosion at the facility, or on the vessel itself. To maintain a tank within its limits for pressure requires improved cargo vapor venting. Care must be taken not only to exclude air, but to prevent structural failure as well. The rules conform to existing basic regulations for sizing tank vents. One example is the requirement that venting accommodate one and one-quarter times the loading rate, which is also a requirement of the International Convention for the Safety of Life at Sea (SOLAS). However, unlike SOLAS, when a vapor emission control system is used, pressure vacuum valves cannot be bypassed during loading and must be able to provide sufficient capacity at the loading rate. Moreover, specific requirements for valve venting have been added. For example, a valve must open between the tanks allowable working pressure and about 1.0 psi. The valve must also open between the allowable tank vacuum and approximately 0.5 psi. Another new requirement is that pressure vacuum valves be constructed so that they can be inspected for free operation and proper closing. Tank pressure and vacuum limits must also be maintained by alarms, which are intended to prevent unnecessary opening of the vent system. Back-up alarms are not necessary with this system. Continued on page 12 Inland tanker helps unload liquid cargo from large parcel tanker at a European port. Like all chemical carriers, these vessels must carry out vapor control measures as required. Photo by Aerocamera Hoffmeester. Continued from page 11 A fire on board a vessel is addressed by protecting vents with flame screens and by shutting off and isolating the inert gas system during loading. To protect a tank's structure from an overflow of benzene, a high-level alarm and an overfill alarm, along with closed gauging, which may be portable, are required. The high-level alarm need not be independent of the gauging. Implementation of these rules has already introduced some problems. Alarms which are not "tank-specific" have been installed on vessels. When loading is controlled on deck by manual valves, a general, or "summary" alarm on deck is of limited value. A summary alarm on deck is only appropriate where loading is controlled remotely from a control room with tank specific indications of high-level and overfill conditions. Certain requirements common to handling of all flammable fluids is necessary. Hoses and loading arms connecting to the vessel's vapor emission control system must be electrically continuous, and there should be an insulating flange at the shore connection. Furthermore, vapor lines should be designed so that condensate is returned to tanks. The vapor emission control system connection from shore to ship must have a lug on the fitting to prevent accidental loading of liquid through a vapor control manifold, which would produce a severe static hazard. (A lug is a piece of metal on one-half of the connection that fits into a corresponding part on the other half.) In addition to the lug, clear marking of the vapor connection is also required. There are still areas that are not specifically addressed. For instance, there is no requirement for length of training. There are no international standards for certification of training, which may be provided by vessel operators. The Coast Guard hopes that the International Maritime Organization (IMO) will develop such standards. Although there is no independent review program set up for the training, a drill program must be in place which covers both normal and emergency operating procedures. International regulations The Coast Guard's work on the vapor emission control system has been considered by the IMO's Subcommittee on Bulk Chemicals, which forwarded a draft of guidelines for marine vapor control systems to the IMO's Maritime Safety Committee for adoption. There are two major differences between the bulk chemicals subcommittee's guidelines and the Coast Guard safety rules. The subcommittee recommends two separate devices -- one for tank level gauging and one for an overfill, but only the overfill device has an alarm. The Coast Guard requires that the two separate devices each have an alarm. Also, unlike the subcommittee, the Coast Guard requires pressure sensors on all vapor return lines. Other than these differences, the IMO guidelines and the more detailed Coast Guard rules agree in principle on all major areas of vessel vapor emission control systems. Conclusion The safety features of vapor emission control systems should ensure that the loading of benzene will not endanger a vessel's crew or the general population residing or working in the vicinity of marine terminal operations. The rules should also serve as a model for future regulation of collecting vapors from other cargoes. The previous two articles on benzene hazards and vapor control are reproduced in an edited form from MariChem 91, the ninth conference on transportation, storage, handling and distribution of bulk chemicals, with the permission of Gastech Rai LTD, 200 Tottenham Court Road, London W1P 9LA. Program management A strong commitment to the safety and health of every employee is evident at the Coast Guard's highest levels. In May 1991, the commandant ordered that Coast Guard commands conduct an all-hands "safety standdown" (oneday safety self-examinations) by June 30, 1991. The initial need for a comprehensive Coast Guard industrial hygiene program was highlighted by a study conducted in the early 1980s by the National Cancer Institute on the incidence of occupational disease in Coast Guard marine inspectors. This study concluded that there was a significant increase in the incidence of certain diseases among these inspectors. Several topics of concern are now being addressed. As a result of a ten-year industrial hygiene study of chemical exposures to workers in the maritime industry, and with the recommendations of the Chemical Transportation Advisory Committee, the Coast Guard is issuing a Navigation and Vessel Inspection Circular (NVIC) scheduled for publication in 1992, which outlines a recommended industrial hygiene program for merchant mariners. Many facets of the Coast Guard in-house safety and occupational health program discussed in this article are similar to the type program recommended for the maritime industry. Continued on page 14 A revision to the Safety and Health Standards section of the Coast Guard Marine Safety Manual will refocus attention on better internal risk management. Safety and occupational health concerns will be included in revisions to NFPA 306 (Control of gas hazards on vessels See page 2), and will benefit both Coast Guard and industry personnel. Participation in a longterm Shipyard Employment Standards Advisory Committee project to rewrite 29 CFR 1915 (See page 1) into a single source standard for safety and occupational health in shipyards will indirectly improve the safety of Coast Guard marine inspectors. Training The success of the safety and occupational health network greatly depends on the effectiveness of training conducted at the Marine Safety School in Yorktown, Virginia. Every marine safety course includes some aspect of safety and occupational health training. For example, port safety and environmental response personnel are taught to use basic toxic vapor sampling equipment, and marine inspectors learn to recognize confined space entry hazards. This training also prepares the students to assume the collateral duties of unit safety and occupational health coordinators. They provide an essential link with district coordinators. A marine safety and occupational health coordinator is assigned to each Coast Guard district office. These professionally trained individuals provide technical support to the Marine Safety Office (MSO) commanding officers, who are responsible for marine safety personnel assigned to their units. The district coordinator visits the field units regularly to perform measurements of recognized chemical, noise and heat stress hazards. The data is analyzed and compared to accepted health standards to evaluate degrees of hazard. Field support model The Second Coast Guard district, headquartered in St. Louis, Missouri, has what is considered a model safety and occupational health program begun in 1989. Three levels of commitment are responsible for the success of this program. 1) Executive level commitment Funding provided by Coast Guard headquarters and policy provided by the second district commander was an essential combination. 2) Field command acceptance Each commanding officer in the second district was already strongly committed to worker health and safety, and many of them were anxious to prove that carrying out the program would improve their job performances. Establishing written policy reflecting a risk management strategy instead of the more traditional specification standards checklist increased support among commanding officers. 3) Worker acceptance Spending money and writing standards does not alone guarantee an effective safety program. Workers who recognize the personal benefits of following safe work practices, wearing protective equipment and preparing for hazards are less likely to cut corners when the boss isn't looking. The second district's safety program has been reinforced by frequent field unit visits by the coordinator who audits programs, inventories equipment and identifies hazards. Visits targeting hazard assessment during routine |