Peek Solutions

Pipeline Design, Operational Integrity Assessment, and Support Solutions

About us

Peek Solutions, an independent consulting company founded by Ralf Peek, provides pipeline integrity solutions and assurance support to the energy industry, including the application of structural reliability methods to assess and ensure integrity.

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Zero Radius Bend (ZRB) buckle trigger
A zero-radius bend (ZRB) trigger that was installed for Sarawak Shell Berhad's B12 pipeline. (From Peek & Kristiansen (2009)).


Our services include:

Our services include the design and assessment of subsea pipelines for lateral and/or upheaval buckling, arctic pipelines subject to ice gouging, stamukha loadings and/or thaw settlements, and pipelines crossing active faults, as well as more routine design and assessment.

Ralf Peek has over 30 years of experience in the area of structural reliability assessment and the estimation and assessment of uncertainties affecting structural performance in order to ensure that safety margins are adequate to cover such uncertainties. His specific experience includes:

  • Reliability-based design of buried arctic subsea pipeline against loading by ice keels gouging the sea floor
  • SRA for pipelines subject to lateral buckling under thermal expansion
  • Operating pipelines subject to extreme conditions (for example, turbidity current loading)
  • Probabilistic response-based seismic loading assessment criteria
  • Nuclear containment structural reliability assessment

Peek Solutions can also coordinate and deliver Quantitative Risk Assessment (QRA), where necessary arranging for inputs on hydrocarbon release modeling from others. (QRA includes assessment of the consequences of failure as well as the probability of occurrence, and typically involves integration of multidisciplinary inputs, as well as inputs based on local knowledge into a model).

Reasons to perform a Structural Reliability Analysis (SRA) or Quantitative Risk Assessment (QRA) could include:

  • Extreme loadings are encountered such as ice, or geohazard loadings for which there are no established design methods and criteria.
  • Operating conditions (e.g. wet, sour service) can strongly affect the deformation capacity of the pipe.
  • Consequences of failure could be exceptionally severe.
  • New technology or a new concept is being used for which there is limited experience, and ingredient uncertainties affecting the performance are different from those for standard technology.
  • Where new, more reliable technology, inspection or assessment methods are used whereby uncertainties are reduced, and an adjustment in the required safety margins could be justified.
  • Value of information analysis under uncertainty in essence consists of performing SRA or QRA with and without the information so that the value of the information can be assessed. Such “information” might consist for instance of a (full scale) testing program, or other investigations to reduce uncertainties.
  • The loading for a pipeline is somewhere in between load- and displacement-controlled, so that existing criteria for either of these cases is not directly applicable, and a case-specific calibration of the required safety margins is needed.

SRA and/or QRA ties together a number of aspects of design, specifications, fabrication and installation methods, monitoring, inspection and maintenance, and contingency response procedures, as all have a bearing on reliability. To include all these aspects properly typically requires a muti-disciplinary team, with expertise that typically cannot be found within a single company. Peek Solutions will assemble and engage such a team (e.g. by subcontracts), drawing from a network of specialists, as well as drawing from customer’s expertise, practices and procedures.

In SRA’s statistical data are used to quantify uncertainties. However, in most cases there are important uncertainties for which statistical data are not available. Indeed, these dominate more often than not. Ignoring such uncertainties, or making the SRA conditional upon certain assumptions about such uncertainties can be dangerous. Therefore, Peek Solutions will assess all uncertainties, rather than only the ones for which statistical data are available, and quantify them by informed engineering judgment, engaging specialized external experts as appropriate.

Despite the guidance available from design codes, the design process relies significantly on engineering judgment to define suitable analysis methods, and the associated assumptions, and approximations. Such judgments should be based on a knowledge of the conditions for which the safety margins in the design code have been calibrated, and how they may or may not differ from the conditions for the design under consideration. Safe and economical design requires not only state-of-the-art or beyond analysis methods, but also an understanding of differences between model and real behavior, their impact, and safety margins needed to cover the associated uncertainties. Peek Solutions can help to assure that such issues have been adequately addressed for pipeline designs where special challenges are involved.

Design reviews can sometimes raise issues at a time when this can have a deleterious effect on project schedules. A better alternative can be to develop a robust design approach from the onset. This can be done by engaging design review at the early stages, or even by developing a Design Specification prior to FEED (Front End Engineering Design) or detailed design.

The Design Specification includes design code interpretation (if applicable), analysis methods, and assumptions and approximations to be made, together with a pertinent example to illustrate these. Further it can include any testing programs, e.g. in the form of additional welding procedure qualification requirements to assure girth weld integrity under strain-based design conditions, or special in situ tests to reduce the uncertainty associated with pipe-soil interaction. Where necessary the safety margins in the Design Specification are calibrated based on structural reliability assessment to ensure that a specified target reliability level is achieved.

In addition to design, Peek Solutions supports installation (where this can affect performance), and specification and interpretation of as-built and/or as-laid surveys.

In some cases it may be expedient to perform quick evaluations of a number of concepts in order to focus on the most promising ones, or check the feasibility of an innovative one which could deliver considerable life-cycle savings, but for which there is limited or no experience. Peek Solutions can help in this process to conceive, identify, and/or assess innovative concepts. For instance, inventions by Ralf Peek include:

  • The Zero-Radius Bend (ZRB) method to reliably trigger lateral buckles in order to safely accommodate thermal expansion. This method has been successfully adopted for a number of high-temperature subsea pipelines for Sarawak Shell and others. According to a review of methods to trigger buckles for controlled thermal expansion by the Safebuck JIP, this ZRB is the only one with 100% success in triggering the buckles as intended.
  • The Pipe-Clamping Mattress (PCM) to stop pipeline walking (cf. Frankenmolen et al. (2017)). This provides an effective alternative to rock dump to restrain a pipeline axially so that it will not creep like a worm under cyclic thermal expansion and contraction, thereby threatening the integrity of end connections.

To make innovation feasible, it needs to be assessed at an early stage. Peek Solutions can help by developing and assessing a feasibility-basis design at a level of detail that is sufficient to expose any devil that may be hiding in the details.

Peek Solutions’ ambition is to contribute to improved understanding and modeling for pipeline integrity assurance, not only by its own R&D efforts, but also by being at the interface between academic research and applications to the industry, in order to make better use of academic research, but also to influence academic research programs towards matters relevant to pipeline integrity.

Structural Reliability Assessment (SRA) provides an excellent framework to capture and quantify improved knowledge from R&D programs in terms of reduced uncertainty. The economic benefit this generates can then be assessed by a Value of Information Analysis (VIA). Conversely, SRA and VIA can also point to areas where R&D is most fruitful.

Ralf Peek has experience with code development and application for Finite Element Analysis, having developed the NPEX code while at the University of Michigan, and further developed it at Shell as a workhorse for pipeline upheaval and lateral buckling analysis. Using NPEX as a starting point, Peek Solutions can efficiently develop codes for specific applications, such as lateral buckling analysis, buried pipeline subject to ice loading or offset at a fault (with the soil modeled by springs), or calculation of pipe deformation capacity without local buckling.

Experience also includes the development of a material subroutine, VUMAT, for ABAQUS/Explicit to model undrained or drained saturated soil behavior during ice gouging over a buried pipeline.


These publications include “unrestricted” reports released by Shell in 2016, as well as other material. If used, the former shall be referenced as a Shell report. In some cases the PDFs include attachments with programs in source and/or Windows executable form.

This was originally developed at the University of Michigan in Ann Arbor with funding from the US National Science Foundation, with special capabilities for challenging structural stability problems (1987-95). It was further developed at Shell for pipeline problems involving reeling, upheaval buckling, lateral buckling, and was also used to establish forming limits for down-hole tubular expansion, as required to achieve a mono-diameter well (1995-2016).

The document available for download is not intended as full documentation and user manual for the program, but it does include references to published documents with specific applications of NPEX, as well as the source code, and 32-bit and 64-bit executable versions of NPEX running under windows.

Since its release in 2016, NPEX has been further developed and documented. Much more detailed as well as up-to-date documentation is provided in the file Npex.pdf in the 5.2MB Windows zip file provided. Npex.pdf includes references to other files also included in the same zip file for further details. The Word version, Npex.docm, contains visual basic whereby after selecting a file name, Control-O will open that file, but that will only work if the visual basic is edited to replace all occurrences of "C:\Users\Ralf Peek\Documents\w\pex\" by the pathname of the folder containing the files extracted from the zip file provided. However, the updated source and executable files are not included.

The effect of concrete coating on strain concentration in pipes, accounting for limited bond strength between the pipeline and the weight coating. NPEX implementation, and testing of the method by Verley and Ness for this. (This allows this concrete to be included in simulations of lateral buckling, or ice gouging over a buried pipeline, for instance).

Pipe-soil interaction model to account for soil berms thrown up by pipelines as they sweep over the seafloor during lateral buckling. This model is implemented in NPEX.

Analytical Solutions for Pipeline Walking developed in 2002 for loading by the most severe conceivable loading, consisting of a sudden surge in temperature that propagates down the line. (These solutions were developed before those of the Safebuck JIP, and were available to the Safebuck JIP, but could not be referenced in those days). They also include solutions for the maximum restraint force to stop walking and the optimum location of the restraint. However, they are based on idealized, and extreme conditions. Whereas they help in developing a feel for the problem, for practical applications, it is recommended to use numerical methods, accounting for more realistic temperature histories, as well as other effects such as possible interactions between pipeline walking and lateral buckling).

Program for smoothing of survey data describing the Out-Of-Straightness (OOS) of a pipeline profile for upheaval buckling assessments. This calculates the best fit structural profile, where a structural profile is any profile that can be achieved by an initially-straight, linearly elastic pipe under downward forces which are limited to the gravity loads on the pipe, and upward forces which can be anything anywhere. (For upheaval buckling assessments SMOOP has been used as a pre-processor, followed by NPEX to perform the upheaval buckling assessment accounting for non-linearity due to the inelastic behavior of the steel, and pipe-soil interaction. This program was developed around the year 2000 when it took hours to run on the PCs of those days, but it is a matter of minutes or even seconds now. Furthermore, the latest version enables a multi-grid approach, that can make the solution process more computationally efficient).

This paper on the effect of reeling and infill under a pipe on upheaval buckling was presented and distributed at OMAE 1998 in Lisbon, but not included in the conference proceedings.


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