Approach allows for robust, flexible valve protection

As part of its longer-term response to these events, Transierra developed and implemented a pipeline and facilities integrity management program for GASYRG, which runs from southern Bolivia to the Rio Grande compression station in Santa Cruz and is part of the gas export system to Brazil.

Essentials of this program included:

• Data management.
• Materials, design data.
• Data integration.
• GASYRG performance data.
• Change management.
• Operating procedures.
• Mitigation, repair.
• Risk assessment.

The program established a base line risk analysis with criteria established in ASME B 31.8S regarding threat categorization (time-dependent, time independent, and stable). Third-party actions, however, fell below the critical-alert level in the resulting risk matrix.

New scenarios

The social unrest prompted Transierra to examine various alternatives for improving protection of its installations and guaranteeing operational continuity, despite third-party damage having been classified by the threat matrix as only a moderate risk. Transierra's resulting contingency plan rested on three fundamental elements:

• Physical security for the facilities.
• Mitigation of further incidents.
• Timely reaction to events.

Engineering development followed these guidelines:

Robustness, security against malicious acts of third parties.
• Functionality, aesthetic integration.
• Operational and maintenance ease.
• Concealed access.

Engineering concept

These criteria guided systematic development of detailed engineering for mechanical protection of 11 GASYRG safety valves. Operations, maintenance, and security personnel all contributed to the process of protecting the valves without disrupting inspection and maintenance routines. The resulting model consisted of a sliding box sectioned in half, with the two halves separating at the center and sliding in opposite directions to allow access (Figs. 1-2).

The structure consists of a metal skeleton made of square tubes, 0.25-in. thick metal plates, eight fixed wheels on each half of the box, and two metal 6-in. by 15-ft W-type rails (Figs. 3-4). The metal skeleton inside the box prevents metal plate deformation and adds rigidity to the assembly (Fig. 5).

Engineering design applied international standards for bulletproof armor to the metal structure protecting the valves. Standards used included EN 1063 (European Community Ballistic Standard), UL 752 (Underwriters Laboratories Ballistic Standard), NIJ 108 (US National Institute of Justice Standard) and NOM 142 (Mexican Standard) and specified steel plate thickness of 0.125-0.500 in.

This structure's functional criteria led to selection of 0.25-in. thick steel, providing ASTM A-36 Level IV protection able to withstand assault with intermediate level weapons (.38, .44, and 9-mm pistols and assault rifles).

Foundation design accounted for the need to support the entire protection structure and also act as an additional enclosure on the lower perimeter of the containers. Design adopted a maximum weight (dead and overload) of 2,300 kg distributed among four foundations and the perimeter cord on which the sliding metal box lies. When the metal box is closed it rests directly on the perimeter cord; when it is open each half rests on two foundations and two cord points. When the box is completely open, it distributes its load across eight points, four points of support on the cord and the remaining four points of support spread over the four foundations (Figs. 6-9).

Engineering also sought to have an opening system hidden from immediate sight and with double lock capabilities for added security (Figs. 10-11). The first lock functions as a gate at the top of the box which opens to a second, Allen-type, security system.