October 2010 Vol. 237 No. 10


SHRIMP Helps Utilities Create DIMP Plans

John Erickson, American Public Gas Association, Washington, DC

Each operator of a gas distribution system must develop a written Distribution Integrity Management Programs (DIMP) plan no later than Aug. 2, 2011 under a rule issued by the Pipeline and Hazardous Materials Safety Administration (PHMSA) on Dec. 4, 2009. This rule will have a major impact on gas systems – perhaps the most significant impact since the federal government first started regulating pipeline safety in 1970. Required elements of a DIMP plan have been described in previous articles – this article focuses on one resource available to assist in creating a written plan meeting those requirements.

In 2005 the American Public Gas Association (APGA) created the APGA Security and Integrity Foundation (SIF) to assist small operators to comply with their security and pipeline safety responsibilities. “Small operators” includes not only natural gas utilities but also master meter systems and propane piping systems that fall under the jurisdiction of pipeline safety rules. Initial efforts focused on training and operator qualification, but in 2006 when Congress mandated that PHMSA issue DIMP rules, the SIF, with support from PHMSA, began developing a model DIMP plan. An advisory group comprised of federal and state pipeline safety regulators plus industry members was formed to guide the project. With LIMP, TIMP and DIMP already familiar acronyms, “SHRIMP” was proposed as an appropriate term for IMP for small systems. “SHRIMP” stands for Simple, Handy, Risk-based Integrity Management Plan.

Early on, the advisers decided to make SHRIMP much more than just a model plan. They envisioned a product that works like tax preparation software – asking questions about the design, construction, operation and maintenance history of the distribution system and actually filling in the model plan template based on answers and choices provided by the user.

Technical Toolboxes, Inc. was selected to do the programming and Viadata and Heath and Associates were contracted to provide technical support. APGA provided the project manager and additional technical support. After three years in development, SHRIMP was released on Aug. 2, 2010 as an online tool that operators of gas distribution systems may use to create their written Distribution Integrity Management Plans, customized for the unique risk factors of each system. While intended for small operators, many large operators have also found that SHRIMP can play a vital role in developing their plans as well.


The first step is to log onto SHRIMP and enter a username and password. Only registered users can access SHRIMP and users can only access the system for which they are registered. Individuals can register for more than one system and a system can have more than one user with access to it. These are all confirmed after the user signs up for SHRIMP at www.apgasif.org.

After logging on to SHRIMP, the user goes through seven steps to generate a customized written DIMP plan. The user first picks which system it is from a list of all distribution systems taken from the PHMSA Distribution Annual Report database. Because the annual report includes information on pipe materials and leak causes, SHRIMP already knows a great deal about the user’s system.

The select settings command lets the user specify the system name as it should appear in the written plan, how far back in years leak repair and other data will be entered and the interval, up to five years, for reviewing the DIMP program.

The next step is to complete each of the eight threat assessment interviews. These interviews ask questions about the design, construction, operation and maintenance history of the distribution system, e.g. the “knowledge of the infrastructure” required by the DIMP rule. That knowledge may reside in written records or in the heads of the personnel who operate and maintain the system on a daily basis. One of the major benefits of SHRIMP is to involve field personnel in the DIMP plan development process without requiring them to become integrity management experts – the integrity management expertise lies in the SHRIMP program.

At the start of each threat, SHRIMP lists the inspection and maintenance records that the user will be asked questions about during the interview. Some questions are used to determine what followup questions to ask. If an operator has an all-plastic system, questions about cathodic protection levels and most corrosion questions will be skipped. Some questions are used by SHRIMP to recommend whether it makes sense for a user to subdivide the system into two or more sections. Subdividing makes sense when different parts of the system have different risk characteristics.

SHRIMP requires the user to subdivide for some threats like corrosion, where there are different threat assessment interviews depending on the material of construction and whether the piping is coated and/or cathodically protected. The user can further subdivide the system as he or she sees fit. The downside of subdividing is it makes the process longer as the threat interview must be repeated for each subsection. The benefit of subdividing is that, if, at the end of the process additional actions are required to address any threat, those actions can be limited to the problem portions of the system. For instance, an operator would not want to replace all plastic pipe just because a few miles of it is a type of plastic susceptible to brittle fracturing.

The SHRIMP Risk Model
Most of the threat interview questions are aimed at determining the probability that a failure will occur due to one of the eight threats, and if a failure were to occur, how severe would be the consequences. In creating the interviews, SHRIMP developers relied heavily on the guidance for DIMP developed by the Gas Piping Technology Committee (GPTC). SHRIMP assigns a score to the answers provided by the user which results in an overall probability and consequence score for the threat to each section of the system. Weighting for each question was based on the consensus of the subject matter experts on the SHRIMP advisory group.

After the user has completed all eight threat assessments for every section of the system, SHRIMP displays the threats and sections in the order from highest relative risk to lowest based on the scores assigned to each section by the risk ranking model. The user is asked to validate that SHRIMP’s rankings make sense to the user. Users are encouraged to move threat sections higher or lower in the order based on their knowledge of the system, but must enter an explanation of the thought process behind these moves and that explanation entry appears in the written plan.

The SHRIMP Written Plan
The table of contents for the SHRIMP written DIMP plan has a section for each of the seven elements required in the DIMP plan. Some of the sections contain boilerplate text but most are placeholders for text that the user will either create or select from menus offered by SHRIMP during the process of developing the written DIMP Plan.

DIMP Table of Contents.

For example, Section 6.1 Mandatory Additional Actions has placeholders for the two mandatory provisions of the DIMP rule – installation of excess flow valves on single-family residences and leak-management procedures. Every operator’s plan must address these two provisions regardless of the outcome of the threat-assessment process.

For excess flow valves, the user selects from two options, either 1) insert the EFV installation policy written by the SHRIMP developers or 2) enter a cross reference to an existing EFV installation policy.

Excess flow valve and leak management options displayed in DIMP.

For leak management there are three options: two pre-written policies residing in SHRIMP and a third option to cross reference an existing leak management policy. Depending on the option chosen by the user, the appropriate text is inserted into Section 6.1 Mandatory Additional Actions of their written plan.

For risk-based additional actions, e.g. additional actions in areas where the threat assessment process indicates a high relative risk, SHRIMP also offers at least one option for additional actions the user can select to address the threat. Based on information collected by SHRIMP during the threat assessment interviews, SHRIMP may suggest one or more additional actions that would be most effective to address the threat, or suggest that some actions would not be effective. SHRIMP always offers the user the option to develop his or her own additional actions or to put a cross reference in the DIMP plan to actions already being taken to address threats.

The last step within SHRIMP in creating a DIMP plan is to select performance measures. Section 7.1 includes boilerplate text for the six mandatory performance measures listed in the DIMP rule. Section 7.2 will be populated with performance measures specific to measuring the effectiveness of the additional actions selected by the user. SHRIMP will offer at least one pre-written performance measure the user may choose, or users can create their own performance measures.

The Finished Plan
At the end of the process, the placeholders in the written SHRIMP model plan will be replaced with text describing why each threat is or is not significant on each section of the system, the relative risk rankings of the sections and the actions the user has selected to address the highest risks. The plan can be downloaded as a Word or pdf file. There will still be additional work to be done to ensure the plan addresses potentially more stringent state regulations and each user will need to consider how it will implement any actions described in the plan.

The only thing small about SHRIMP is its cost. SHRIMP is a complete DIMP compliance program, meeting all the requirements of the DIMP rule. While intended for small utilities it may be used by ANY utility regardless of size. Care has been taken to ensure that the DIMP plans developed by SHRIMP fully address all the requirements of the rule – the same high standard that applies to all utilities from the very largest to the smallest. It is designed to draw out the knowledge of infrastructure from the people who operate and maintain the system on a daily basis and are most familiar with system problems, without requiring those people to become DIMP experts. For a small system that process may result in the final plan, whereas larger systems with central engineering and compliance staffs can use it as a way to get input from field personnel into the DIMP process.

For utilities with 1,000 or fewer customers, SHRIMP is free. For larger utilities, the cost is minimal, with proceeds used to provide technical support and enhancements to SHRIMP. So far, over 360 systems including municipal utilities, master meters, propane piping operators and some of the largest investor-owned utilities have obtained licenses to use SHRIMP Enhancements to SHRIMP are already under way. The rule requires that the DIMP program undergo a complete re-evaluation at last once every five years. SHRIMP will walk the user through this process, verifying and documenting that all the key areas of the plan were reviewed and either confirmed to still be accurate or updated by the user. The cumulative leak repair data by cause and by material type will also be analyzed for trends to improve the risk ranking model. Feedback from users has already provided more ideas to make SHRIMP more valuable. Information about SHRIMP is available at www.apgasif.org.

John Erickson is vice president of operations for the American Public Gas Association. He can be reached at 202-464-2742.

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