Services Mechanical


AXIOM’s Mechanical function specialises in the design and engineering assessment of pressure systems. Our Mechanical Engineers have been providing support to owners and operators of high hazard plant for over 20 years, working closely with our clients to improve their assets’ life and reliability, whilst ensuring industry best practices are followed.

Our team is highly qualified and skilled in working with equipment which falls within legislative requirements including PSSR and COMAH. With a wealth of experience, our capabilities include working with pressure equipment design and fitness for service codes such as PD5500, ASME VIII, ASME B31.3, API 579 and BS 7910. Service offerings include:

  • Fitness for Service (FFS) Assessments
  • Design of Equipment Repair and Modification
  • New Equipment Design
  • Mechanical Data Sheet Development
  • Finite Element Analysis (FEA)
  • Pipe Stress Analysis
  • Third Party Review Services
  • Design Verification Certificates (DVC’s)
  • Fracture Mechanics

AXIOM’s Mechanical team sits alongside our Materials Engineering and Process Safety functions, to form AXIOM’s Engineering Services Division. The Engineering Services Division is supported by our UKAS accredited Inspection team, together forming a multi-disciplined service offering which allows AXIOM to deliver solutions of real value to our clients.

Take a look at our Mechanical service offerings for further details on how we can help you.

AXIOM’s Mechanical Engineering department specialises in undertaking Fitness for Service (FFS) assessments of process equipment. As well as referencing an asset’s original design code to assess FFS, we routinely conduct Level 1, 2 and 3 API 579 assessments for a range of equipment types and clients in high hazard environments. The four main deterioration mechanisms that often contribute to the ageing of pressure systems are:


Corrosion can manifest itself as external, such as corrosion under insulation (CUI), or alternatively internal corrosion may occur due to a breakdown of a lining or process up-set. Corrosion may be general, localised or classified as pitting. AXIOM’s Mechanical Engineering department routinely supports our clients by investigating the suitability of general thinning, locally thinned areas (LTA’s) and pitting defects.


AXIOM is well versed with the fatigue assessment methods provided in design codes such as PD5500, ASME VIII and BS EN 13445. Where possible, stresses required as inputs for fatigue studies can be quantified via formula-based methods, or where a greater level of accuracy is required, can be quantified using Finite Element Analysis (FEA), and used with codal SN curves to investigate fatigue life.

Fatigue is a major deterioration mode and needs careful handing to understand and evaluate the consequences of operating plant under cyclic duties. AXIOM has been historically successful in correlating our assessment models against real life situations, and pride ourselves on our ability to help make accurate predictions and specify modifications that can extend equipment life and improve fatigue performance.


High temperatures often cause creep, which can limit the service life of equipment. We have extensive experience of evaluating this mechanism and helping clients manage and extend the life of high temperature pressure systems.

Using our knowledge of design codes combined with both FFS standards, and aided by specialist software, AXIOM’s Mechanical function is able to tackle and assess complex deterioration mechanisms to the highest standards. As well as the more common deterioration modes discussed above, our team also have notable experience of investigating an assets FFS when subject to the following damage mechanisms:

· Dents

· Gouges

· Erosion

· Fire Damage

· Laminations

When equipment cannot be deemed fit for service and requires repair, AXIOM’s Mechanical team can specify the design of temporary and permanent repair procedures and modification solutions. AXIOM is well versed with design, inspection and repair codes, which can be referenced when specifying equipment modifications, ensuring compliance with required industry standards and directives. Repairs and modifications can be specified in accordance with a wide range of international standards, including:

  • ASME PCC-2
  • PD 5500
  • ASME VIII Division 1
  • ASME VIII Division 2
  • BS EN 13445
  • ASME B31.3
  • API 510
  • API 570

Where required, calculations and computational analysis can be performed to demonstrate the suitability of modifications and repairs. AXIOM’s Mechanical team provide draughting services, developing Engineering Drawings that ensure clear definition of a repair or modification, so that the required industry standards are satisfied regarding:

  • Mechanical Design
  • Materials Selection
  • Weld Details
  • Non-Destructive Testing
  • Quality Control
  • Pressure Testing
  • Stress Relief

AXIOM’s Mechanical team boasts over 15 years’ experience of using ANSYS Finite Element Analysis (FEA) software, which provides a more in depth means of assessment compared with traditional formula-based approaches. FEA is used to inform the design of new equipment or the design of repairs and modifications, as well as to investigate the fitness for service (FFS) and remnant life of aging assets. It offers an in-depth analysis methodology, which can be used when alternative assessment methods cannot be applied or provide unfavourable results. A range of failure and deterioration modes can be assessed in line with codal guidance, ranging from basic structural integrity assessments through to the study of more complex failure modes such as creep and fatigue. A range of analysis techniques can be applied depending on the problem in hand, including non-linear and thermo-mechanical. As a matter of course, we consistently keep up-to date with the latest guidance and rules concerning the use of FEA in line with pressure system codes such as the ASME standards and British Standards and European codes.

AXIOM uses industry recognised software to analyse and design piping systems, ensuring compliance with major European and American design codes. The outputs of pipe stress analysis can also be coupled with fitness for service codes, such as API 579, to better investigate the integrity of aging systems.

Pipe stress analysis can be used to:

  • Inform the design of new pipework
  • Verify the suitability of system modifications
  • Determine the suitability of proposed system re-rates
  • Investigate the fitness for service (FFS) of aging pipework
  • Quantify pipe system loads to inform other studies
  • Investigate the root cause analysis of reliability issues.

Assessment can consider static loads (pressure, thermal and self-weight) and dynamic loadings, such as surge. In addition to determining codal stresses within the pipework, a pipe stress analysis can be used to determine loads acting on connected assets, for example vessels or storage tanks and pipe supports. Pipe stress analysis provides an efficient means of ensuring consideration is given to all applicable loads and stresses developed within a system. AXIOM’s Engineers have experience of assessing both metallic and non-metallic piping systems.

AXIOM’s Mechanical Engineering department can assess crack stability and growth rates in accordance with the rules of BS 7910, with access to TWI’s Crackwise software. The stability of existing defects can be investigated, or alternatively tolerable defects sizes can be quantified to aid future inspections. AXIOM’s Mechanical team can work with our Inspection function to determine what size defects can actually be identified using modern NDT techniques. This collaboration has been successful when investigating the feasibility of clients moving assets onto non-invasive inspection regimes.

AXIOM’s Mechanical function routinely support our clients with the provision of third-party review services. This may apply to reviewing design documentation associated with the provision of new equipment, or alterations to existing assets.

AXIOM is able to ensure risks associated with fabrication and modifications are minimised by verifying design requirements meet industry standards as well as ensuring appropriate levels of inspection and testing are performed during and following fabrication and modification works.

Many of our clients whom are of ICI heritage maintain a Design Verification Certificate (DVC) procedure. Axiom’s Mechanical function routinely provides DVC services relating to:

  • Equipment Procurement
  • Plant Modification
  • Asset Fitness for Service (FFS).

For modification procedures and FFS assessments developed in house, a design verification can be undertaken by one of our Chartered Engineers, and a Design Verification Certificate (DVC) subsequently issued.

New Equipment

AXIOM’s Mechanical function can support our clients regarding the procurement of new equipment in the following ways:

  • Mechanical Data Sheet Development
  • Design Code Compliant Calculation Pack Production
  • Design by Analysis (FEA)
  • Fabrication Drawing Production
  • Third Party Design Reviews of Works Completed by Others
  • Design Verification Certificate (DVC) Issue

Mechanical Data Sheets: Mechanical Data Sheets are developed to form a basis of Mechanical Design. These are usually produced following production of a Process Data Sheet, which can be developed by Axiom’s Process Safety function.

Calculation Packs: Calculation packs can be produced to substantiate the Mechanical design of new equipment, such as storage tanks, pressure vessels and heat exchangers. Pressure vessels and storage tanks are typically designed referencing codal design by formula (DBF) methods. AXIOM has access to PV Elite and Finglow software packages, which align with all major pressure vessel design codes.

Design by Analysis

Where new equipment is to be designed with non-standard features and design by formula (DBF) rules cannot be applied, AXIOM is able to use computational analysis, referencing the Design by Analysis (DBA) guidance given in major pressure vessel design codes. Further details of our Finite Element Analysis (FEA) capability can be found here.

Fabrication Drawings: 2D fabrication drawings are developed from 3D model files to aid fabrication. Drawings provide materials requirements, weld details, NDT and testing requirements.

Third Party Reviews – AXIOM can support our clients by undertaking a third-party review of the Mechanical Design Calculations and Fabrication drawings developed by others. Our third-party review services are discussed further here.

Design Verification Certificates (DVC) – For clients of ex-ICI heritage, who still maintain Design Verification Certificate (DVC) procedures, AXIOM’s Mechanical Engineers are well versed with DVC requirements, and can review new equipment design packages accordingly. Our DVC services are discussed further here.

Second Hand Equipment

Often second-hand equipment is available on the market with no design documentation, or equipment is rated for design conditions which differ to our clients’ requirements. In such circumstances AXIOM can undertake retrospective engineering assessments to determine safe operating limits for second hand equipment, or investigate the suitability of equipment being re-rated and / or placed on a different duty to that it was originally designed for.

AXIOM’s Inspection and Process Safety functions can also provide support regarding the procurement of second-hand equipment, for example to verify asset condition or investigate pressure relief requirements.

Supporting the Asset Life Cycle