Figure 1. The Plant Condition Manage- ment System (PCMS) is divided into three phases designed to proactively address deteriorating civil infrastructure and its root cause(s).

Figure 2. Through a risk matrix, evaluators are able to discern the priority level at which repairs are necessary and should ultimately be scheduled for implementation.

Our Petrochemical Industrial Infrastructure is aging at a rapid pace while our demands for the products manufactured by these facilities are increasing even more rapidly. As an Owner, understanding the risk associated with not conducting maintenance on civil infrastructure versus spending the funds on maintenance in order to keep the facilities operating, can involve difficult decision-making "opportunities". As with process equipment, risks associated with potential process interruption by failures of civil infrastructure are weighed and decisions made. These decisions are based on factual historical information of similar process scenarios, effect on adjacent process streams and the facility as a whole. Being proactive versus reactive has been proven, via Risk-Based-Inspection (RBI), to be the best path available to Owners as a means & methods to maintain an operating facility with minimal interruptions.

As a derivative of the RBI, a new tool was developed that addressed the condition of civil infrastructure assets in a similar way to those assets directly involved with the process stream. The Plant Condition Management System (PCMS) is a program developed to proactively address conditions prior to serious developments such as safety concerns and diminished structural integrity. The PCMS effort is divided into three (3) phases (Figure 1). Phases 1 and 2 are aimed at establishing the need of condition assessments in different infrastructure assets, evaluating the causes of current distress, providing conceptual repair recommendations, and defining repair priorities with associated budgetary repair costs. PCMS Phases 1 and 2 can include the evaluation of reinforced concrete, structural steel, masonry and timber structures as well as fireproofing and protective lining systems. Appropriate turnkey repairs, based upon work repair priorities, are executed during the PCMS Phase 3 to accommodate Owner maintenance needs to optimize uninterrupted support service.

The PCMS Phase 1 involves the initial Visual Inspection and Scope Definition for a facility by identifying those assets that are believed to be in a state of apparent deterioration. Initially, Phase 1 consists of a cursory, short-duration site reconnaissance walkthrough (i.e., inventory of existing structures) to define the scope of repair opportunities, identify areas requiring more in-depth evaluation, and exclude structures performing satisfactorily and consistent with their intended service. 

PCMS Phase 2 provides a more in-depth "picture" of what will require repair, how much, and when it needs to be done. Employing a combination of walkthrough and tactile investigatory techniques, evaluators are able to discern with some accuracy, the presence, extent, and through a risk-matrix consistent with Owner/Operator criteria (Figure 2), the priority level at which the repair exists and ultimately scheduled for implementation. A flow-chart relating to reinforced concrete and structural steel structures undergoing a Phase 2 evaluation is presented below: (Figure 3)

Figure 4. Flow chart relating to reinforced concrete and structural steel structures undergoing Phase 2 evaluation.

Establishing Repair Priorities within civil infrastructure along PCMS guidelines cover Safety, Structural Integrity and Durability. A Risk Assessment checklist is a fundamental facet of the PCMS Program that considers two factors, safety and asset performance. The primary objective of the program is Safety which is the prime directive when conditions are encountered that represent hazards to personnel and to a slightly lesser degree, equipment and process streams. Performance refers to the ability of an asset to serve its' intended function.

Figure 4. Two - two drum support structures connected by a common walkway.

For example, faulted cracking in fireproofing and/or exposed structural steel could be considered a loss of fireproofing continuity. Such characteristics would suggest reduced fireproofing protection (i.e., total or partial loss of fireproofing protection). It's important to note that a performance risk could result from multiple combinations of different deterioration manifestations. Similarly, the risk assessment of an element could combine the safety and performance risk (e.g., combination of falling debris hazard with reduced fire protection due to severe cracking).

Case Study: Client Refinery in Oklahoma

Objective

The objective of the PCMS was to assess the existing condition of accessible structural steel pipe supports in designated sets within the entire refinery complex. Distress features in the structural steel and fireproofing were identified, documented, and quantified as necessary. PCMS Phases 1 and 2 established pipe supports of concern by highlighting safety, structural and durability issues. Causes of steel and fireproofing distress were assessed. If readily apparent, repair work priorities were established, conceptual repair recommendations provided and budgetary costs assembled. The Scope was as follows:

• Reviewed available project documents relative to the evaluated pipe supports.
• Reviewed concrete foundation bases, steel base plates, structural elements (i.e., Columns, Beams, Bracing & Connections), and fireproofing.
• Employed Non-Destructive Testing (NDT) including Crack Comparators and Mechanical Hammer Sounding techniques over representative pipe support elements in an effort to detect abnormal acoustic emissions that could suggest hidden distress characteristics.
• Obtained high-resolution digital photographs (authorized by the Client) of representative pipe support distress occurrences within the evaluated areas.
• Collected representative concrete powder samples from fireproofing materials using rotary hammer-drill extraction techniques. Collected samples were submitted for Laboratory Analysis.
• Laboratory Analysis included testing the powder samples for Chloride Ion (Cl^-) Content of Hardened Concrete.
• Established repair priorities based on safety, structural, and durability guidelines consistent with the PCMS program objectives.
• Performed a review of available repair and maintenance alternatives and evaluated cost, effect of working space and installation during process operations.
• Assembled and submitted a written report detailing findings, analysis and conceptual repair recommendations. Budgetary Repair Costs were submitted under separate cover.

It's important to note that the information presented in the report didn't include a structural analysis of the designated pipe support sets because that level of evaluation was outside the scope of the PCMS.

The backbone of PCMS is the use of Data Forms which are employed in the field and implemented in the archival effort. For the refinery Client's Pipe Support Project a collection of nine (9) data forms were created and codified using the refinery plant and pipe support number. The forms' design is composed of a combination of checklist and text fields to expedite data collection efforts. The form header includes the general form name, the refinery plant, the pipe support set number, and the form code. Data forms were used only when applicable. For example, a pipe support set with no fireproofing on any of its elements would not require the use of forms designed to record fireproofing information.

Figure 5. Coke drum support structure switch deck slab octagon penetration exhibiting advanced deterioration due to embedded metal corrosion.

Background

The evaluated Pipe Supports had reportedly been in service for several decades being constructed during the 1940's as part of the USA's War Fuel Refining Effort during World War II. The pipe supports from that era, in general, were constructed of "drill" pipe available at the time. The pipe sections varied between 4" nominal diameter to 6" nominal diameter for the columns, and generally 4" nominal diameter for the beams and bracing. All sections were welded to form small rigid frames as part of the support system.

The use of fireproofing varied, depending on the specific plant Unit and where in the plant the pipe rack was located. Approximately half of the pipe racks during this PCMS investigation did not have fireproofing.

Project

The project started with a PCMS Phase 1, in which Client representatives from each of the plant Units met with representatives from SPS to determine the scope of the task. A walk down of the areas of concern in each of the Units was conducted. This initial visit provided information to determine the final scope for the PCMS Phase 2 work.

The PCMS Phase 2 involved a team of seven (7) investigative specialists (2 engineers, 2 technicians, 3 laborers for support) from SPS. The work was coordinated through refinery Client management from each Unit to facilitate the process of obtaining permits, access work areas, and to monitor/coordinate safety. The onsite work was accomplished in nine (9) working days.

Figure 6. Coker sluiceway within a railway track exhibiting advanced deterioration due to thermal shock, abrasion and embedded metal corrosion.

The SPS personnel were divided into two (2) teams for efficiency of observations and recording purposes. The use of the data forms was implemented extensively to record the degree of deterioration and corrosion, if any, that was observed by the investigative teams. Also, as part of the data forms, photo logs were incorporated to visually document (these photo logs were reviewed & approved by the Client) the observations of the field teams.

At pipe racks with fireproofing, excavations were made at predetermined locations to assess concrete properties, and to observe the amount of steel pipe corrosion and potential section loss. These observations were recorded on the data forms to be later analyzed and included in the final report. Pipe racks without fireproofing were observed for corrosion & distress and duly noted on the data forms to be analyzed later in the office. Approximate quantities for the various repair or member replacement sections were tabulated and incorporated into the final submitted work product.

The PCMS Phase 2 field investigation information was then analyzed with raw data from the field data forms consolidated, and prioritized to determine the extent of potential repairs. The repair recommendations, priorities, and approximate order-of-magnitude costs were included in a Letter Report for each Unit in the refinery. As a result of PCMS Phase 2 activities, the Client determined internal repair location priorities and the budgets required to perform the repairs in the various Units. For the Client's Refinery, it was decided to complete the Priority No.1 & No. 2 items in a single Unit, starting with the Coker Unit.

Repair Program

The PCMS Phase 3 activities included the actual work to perform the needed repairs, initially starting repairs in the Coker Unit. SPS provided engineering and construction management for the Client designated contractors to perform lead abatement (by Client directed contractor), shoring and structural steel reinforcing or replacement. The contractors were under direct contract with the Client. This phase did not have concrete repair, which SPS would have self-performed.

Figure 7. Ultrasonic metal thickness meter checking the thickness of a sphere structural column below the fireproofing for corrosion under insulation (CUI) determinations.

Future work for 2008 will include engineering and construction management in another refinery Unit. The work will be very similar to the work in the Coker Unit. SPS will provide engineering and construction management for the steel pipe rack repair activities. The repairs will include both Priority items No.1 & No. 2 work as noted on the PCMS Data Forms and Letter Report.

Case Study: Client Refinery Coker Support Structures in California

Objective

Concerns with the Coke Drum Support Structures stemmed from visually obvious concrete distress in the forms of cracks, delaminations, open spalls, exposed corroding reinforcing steel bars and failed existing concrete patch repairs in these critical support structures. The objective of the Condition Survey was to assess the existing condition of two (2) reinforced concrete Coke Drum Support Structures by employing a focused tactile Condition Survey effort following a seven (7) step evaluation process:

• Characterize trends of existing reinforced concrete deterioration,
• Compare the existing condition to original construction details, if available,
• Document indicators of apparent structural integrity concerns
• Identify apparent root cause(s) of deterioration,
• Quantify extent of concrete distress,
• Formulate conceptual Turnkey concrete repair solutions, and
• Estimate Order-of-Magnitude costs for established concrete repair solutions

Background

The two (2) Coke Drum Support Structures, each supporting two (2) large Coke Drum Vessels, had been originally designed and constructed in the mid-1950s. The Structures are massive "table-top" conventionally reinforced concrete frame structures with circular penetrations extending through the full 5' thickness of the Switch Deck Slab to accommodate the frustum-cone bottom of the Coke Drum. Over its' service life, a series of seismic upgrades had been installed in the form of FRP Wraps applied to Beam and Column surfaces to stiffen the frame structure. Additionally, a series of poorly planned and executed patch repair program initiatives had been attempted in regions of concrete cracking, delamination and open spalls on both structures. The result of these "repair" attempts only exacerbated deteriorated conditions.

Project

The scope of work was as follows:

• Reviewed available project documents relative to the evaluated Coke Drum Support Structures.
• Performed a visual inspection of accessible concrete surfaces noting areas of concrete cracking, spalling, staining and other significant features (i.e., mapping).
• Using site assembled access scaffolding, performed an acoustic impact survey (i.e., mechanical soundings) in representative areas over accessible concrete member surfaces in an effort to detect subsurface voids and/or delaminations (i.e., internal separations).
• Performed a pachometer survey to determine the presence and orientation of embedded reinforcing steel details. Reinforcing steel configurations detected during the survey were compared to as-designed reinforcing details.
• Performed Non-Destructive Ultrasonic Pulse Velocity (UPV) and Rebound Hammer Testing, ASTM C-597 and ASTM C-805, respectively. These techniques were employed at representative locations to ascertain consistency and quality of the concrete, in-situ, for correlation with the sample recovery program.
• Collected concrete cores using wet rotary diamond core drilling techniques and concrete powder samples using a rotary hammer drill.
• Submitted collected core and powder samples for Laboratory Analysis which included:
  a. Depth of Carbonation Testing: Carbonation depths were determined using a modified phenolphthalein
      pH indicator solution sprayed onto freshly fractured concrete surfaces. Visual observations of the
      resultant spray surface color tints indicated the existing concrete environment and susceptibility to
      corrosion activity.
  b. Chloride Ion Content of Hardened Concrete Tests: Chemical extraction test results determined the
      chloride ion level within the concrete. The detected level is an indicator of the potential electrochemical
      process of embedded metal corrosion within the concrete mass.
  c. Compressive Strength Testing of Concrete Core Specimens (ASTM C-42). Test results provided 
      strength values and were an indicator as to the relative quality of the concrete.
• Performed a review of available repair alternatives for the structure(s) to provide the best long-term serviceability.
• Prepared a "Turn-Key" proposal that addressed the required repairs and met the Client's anticipated repair implementation schedule.

Repair Program

Upon review of various repair options, effect on workspace, and evaluating on-line/off-line concrete repair scenarios, the resultant repair strategy was selected and is described below.

• Worked in association with the refinery Client at preplanning on-line & off-line concrete repair operations providing process access and shielding to critical process assets.
• Installed working platforms (e.g., scaffolding) to provide access to elevated areas.
• Excavated and removed deteriorated concrete materials within perimeter sawcuts and prepared concrete surfaces in accordance with International Concrete Repair Institute (ICRI) and ACI Guidelines. Repairs were performed in an engineered staged sequence pattern.
• Cleaned and protected exposed reinforcing steel bars accompanied by rebar augmentation and/or replacement, as needed.
• Applied corrosion-inhibiting technology within repair product matrices. The application of corrosion-inhibitors within repair concrete mix designs will mitigate further deterioration into the original "sound" concrete substrate and reduce the potential of premature repair failure along the repair "bond-line."
• Installed a passive cathodic protection system employing corrosion mitigating anode technology within repair cavities to arrest potential "halo" corrosion effects.
• Engineered and built unique circular concrete formwork with steel and wood components.
• Assembled mortar-tight concrete formwork at concrete repair locations.
• Reestablished structural section in repair areas by placing very-rapid setting high-quality, dense cementitious repair materials within formed cavity areas using Form and Pump and/or Form and Pour techniques. Repairs to concrete elements did not involve significant volumetric quantities, however consistent material characteristics and properties were necessary. As such, the use of pre-bagged repair concrete materials from reputable manufacturers was used in the repair program.
• Removed mortar-tight formwork after an extended wet-curing period and "dressed" repair areas to match adjacent parent concrete surface contours.

As can be seen by the Case Studies presented above, understanding the scope of work, whether from a global perspective such as when trying to grasp the effects of deterioration on a plant-wide basis or on a critical specific structure level, it's important to employ an engineered approach and critical thinking. Critical thinking comes into play when the information and data are presented in a thoughtful format and enlightened decisions can be formulated on how best to approach crumbling infrastructure.