Rethinking the core principles of pipe-stress and flexibility analysis

Calendar

• Week 1: part 1-2
• Week 2: part 3-4
• Week 3: part 5-6
• Week 4: part 7-8
• Week 5: Example 1
• Week 6: Example 2
• Week 7: Example 3
• Week 8: Example 4

Part 01

Introduction
Seminar program
Mistakes, errors and disasters

The main focus of this seminar is on problems closely related to pipe stress and flexibility analysis.
In the introduction the need for such course will be highlighted and how little-known facts have pointed out towards its importance, like the contribution of piping works in a typical process plant. Also, with the possible causes of design errors, and their contributions to catastrophic consequences, which in some instances have been observed.
Since disasters teach more than successes, an overview will be given of some general individual examples of failures, emphasizing and focusing on the contribution of design errors and discussing consequences.
The purpose is to instrument the development of critical thinking in relation to piping design issues, and its role in solving and preventing potential failures before they occur.

Part 02

Mistakes, errors and disasters, cont.
Introduction to failure analysis

In continuation, the course program will describe in detail, two major failures, analyze and overview the possible reasons which led to catastrophic outcomes.
Further, in the introduction to failure analysis, it will elaborate on the main philosophy behind, extrapolated to having in mind the examples of piping failures.
The main aim is to raise awareness because unless we accept that, Human error is unavoidable, and we all make mistakes that contribute to failures and accidents, we will not be able to fully focus on facilitating doing the right thing in pipe stress and flexibility analysis.

Part 03

Introduction to failure analysis, cont.
Possible causes of accidents due to project related issues
Pipe stress analysis from a global project perspective

Failure analysis will be finalized with, Root cause analysis logic tree, and opening up the subject of where we could expect to have potential sources of accidents associated with project related issues.
The previously analyzed, steps of activities leading to RCA, is a reactive methodology. The intent is to apply the thinking behind, to project related issues and raise awareness of main contributors to possible causes of accidents, with the idea to possibly make influence on prevention.
In relation to pipe stress analysis, particular accent would be made on major failure mechanisms as contributors and on the objectives of stress analysis within the organizational structure and a special place it holds.

Part 04

Pipe stress analysis from a global project perspective, cont.

In addressing the root cause in piping design errors, special attention in this chapter will be paid on interlink between Piping Engineering/Design and Pipe Stress Analysis. This primarily revolves around selecting the right methodology, i.e. Reactive or Proactive, because the overall project results are directly influenced by the chosen methodology in designs closely tied with pipe stress analysis, and which is therefore essential.
Also, the flow of activities for the stress analysis, project related as well as intradiscipline flow of activities will be discussed.
Following, on the example of Gas turbine cooling air system analysis, will illustrate the benefits of computational analysis. In addition to this, explanation from forensic investigation will be given, which has identified the lack of Proactive methodology as the main contributor within the design process, leading to DMW seam weld failure with catastrophic consequences.

Part 05

Piping systems from pipe stress analysts’ point of view

In this chapter focus will be on basic concepts everyone connected with stress analyses should be familiar with, regardless of their function in the design process.
It starts from the purpose of pipe stress analysis, then through basic concepts of stress and strain as well as commonly known stress strain relationship, that the applied calculations and analysis are meant to address. Then it describes the concept of loads and stress types that are going to be used by the codes and stress analysts. Also, defines and describes the requirements for stress engineer in terms of code defined educational requirements, and experience and highlights the duties and responsibilities. Finally in basic terms, focusing on thermal expansion of piping systems, talks about how piping and piping components fail.

Part 06

Typical analysis mistakes

Before stepping into this subject, firstly it is discussed generally about piping, and piping/pipeline types with examples on their peculiarities because of increasingly complex demands that are
imposed on their design. The need to fulfil the pre-set technological requirements with minimal capital expenditure is also briefly addressed. Following, the introduction to the concept of classification of piping elements which are forming the piping system is carried out, based namely on their specific function.
The final attention in this chapter will be, as an example, towards piping elements, essential for controlling the technological process function, and in particular jacketed piping systems.

Part 07

Typical analysis mistakes, cont.

In this chapter, we will elaborate further on other elements forming the piping system, like those which are forming the structural core of the piping system and then, finalizing with most important for us in this course, supports and restraints, elements responsible for maintaining structural integrity and controlling the design life of the piping system.
The second most important subject in this chapter would be in relation to some common mistakes in performing stress analysis. And finally, will discuss most frequent unintended misconceptions about conclusion from analysis results.
From thereon before continuing to the next topic, will reveal the concept of SIFs based on which pipe stress analysis was built.

Part 08

How to properly analyze?

With everything learned so far, we became equipped to wrap-up the process of gaining full understanding, and appreciation of what lays behind the scenes of successful application of pipe stress analysis on projects.
The topic will commence with probably the foremost subject: Selection procedure for determining the scope of pipe stress analysis. Discussing and explanation on this will be carried out, as it is probably equal if not more important than the subject of, choosing the right methodology, because it has direct impact on project outcomes.
More about this important theme if required, can be found in a separate course of study: “ ’Fit-for-purpose’ procedure for creating and managing pipe stress analysis and piping design work”.
We will also link this with subsequently discussing the importance of application of appropriate software tools, and finally to highlighting essential details for appropriate modeling and conceptual settings required for proper analysis.

Example 1

BLOW OFF SYSTEM GAS TURBINE GT11 N2
The analysis will provide answers to the following questions set up by the project:
Question #1: How to do proper analysis although not all
information is available?
Question #2: How to ensure with analysis the integrity of the
design?

Example 2

ANALYSIS OF UNWANTED DEFORMATION OF
HOT AIR PIPE FROM MAIN GAS TURBINE
BEARING
The analysis will provide answers to the following questions set up by the project:
Question #1: Why did the deformation happen?
Question #2: How to defend the analysis and design against false
claims?

Example 3

CRUDE OIL TANK #2 24” NOZZLE N3 –
EVALUATION OF LOADS PRODUCED BY PIPING
– AND DESIGN REQUIREMENTS IN RELATION
TO LOCAL STRESS ANALYSIS
The analysis will provide answers to the following questions set up by the project:

Question #1: “can we connect the piping safely to tanks in its as
is piping configuration”?
Question #2: “can we modify the attaching piping as proposed
and then connect safely to tanks”?

Example 3

TANK 1 (NORTH) - VENT NOZZLE N1 16” –
LOADS EVALUATION PRODUCED BY VENT
PIPING AND – DESIGN REQUIREMENTS IN
RELATION TO LOCAL STRESS ANALYSIS
The analysis will provide answers to the following questions set up by the project:
Question #1: “can we connect the piping safely so “no additional
load” should be applied on Vent nozzle”?