A way to be more knowledgeable

Success has different meanings for all sectors involved in an industrial project. But generally it implies a defect-free implementation of projects according to specifications and codes, on time and on budget.  From our community's viewpoint, a safety is construed as a main sign of a success. So the design should not impose any dangerous to humans and environment. From client's viewpoints, a design system is successful if all safety and technical requirements are met and the project is done on its budget and time. A common word in all above is safety. System should be designed on time and on budget too. Any significant errors in engineering calculations, in both design and construction stages, may lead to a dire consequences or make the project over budget. Besides being too conservative resulting from lack of knowledge may lead to an increase in budget too. For example lack of knowledge required to use WRC-107 may lead to an unnecessary increase in a vessel thickness. Some of engineering’s errors and omissions arise from the following reasons:

• Lack of engineering fundamental knowledge

• Lack of code knowledge

• Lack of required knowledge behind common engineering practices

• Lack of required knowledge enabling engineers to use  some simple and cheap computer tools for calculation and validation effectively

Fundamental knowledge of engineering is the most important and effective tools on which an

engineer’s judgment is based when a challenging issue comes up. For example thickness of a CCO pipe in modeling, load case type for a settlement load, considering corrosion in expansion load case and pressure thrust calculation in various systems are in this category. Moreover it helps engineers in interpretation and validation of software results and can protect them from any dangerous design leading to a dire consequence.

For instance considering pressure thrust and thermal effect on a flexible component such as Victaulic in a software may lead to wrong results. In safety factor calculation in an area, local stresses should be combined with general ones according to the method mentioned in ASME BPVC Sec VIII Div 2. In using that method, fundamental knowledge of engineering plays an important role in selecting of proper stress category types and calculating of intensity or equivalent stresses.

Engineers are bound to follow code requirements as a minimum one. Lack of knowledge in basis of code requirements and criteria may lead to a catastrophe. Having knowledge about code’s scopes, incorporated Safety Factors (S.F) and restrictions is a must for ensuring the design is safe and economic too. When using a part of one code to another code, engineers should pay attention to the S.Fs to make sure an acceptable safety margin is available. Lack of this knowledge also deprives engineers of any opportunity to relax some requirements which make the design costly. For example activating liberal stress or using S-N diagrams mentioned in ASME BPVC Sec VIII in ASME B31.3 needs some engineer’s discretions and knowledge of the code.

There are some common engineering practices or methods which have been using for many years in piping industries. Any blind use of these methods may place engineers in a perilous situation. As a matter of fact, engineers should be familiar to their basis, restrictions and assumptions. Regarding regulations in Canada, engineers are accountable for their design so having knowing about what is going on behind the scene protects engineers who are using the methods. For instance Kellogg’s method has been known and applied for many years in piping industries. Shear stresses are not considered in this method. So using this method for calculation of local stresses at junction of pipe and a fixed trunnion that is under a big pressure thrust load may be a controversial issue. Unless the engineers reach to a conclusion that using the method brings a minimum safety margin to the system. For reaching to this degree of certainty, not only the knowledge of the method is required but fundamental and code knowledge play a determining role.

Engineering practices and methods are a priceless source for engineers who are facing up a challenge or dilemma in designing a system. Moreover, they improve engineers’ knowledge of a team. As a consequence, the whole system is designed in a consistent and safe manner. It can be interpreted as SUCCESS.  These experiences which are known as lesson learns have been acquired by damages or malfunctions resulting from bad designs of previous systems. For example location of some piping components such as on-off valves and reducers may have adverse effects in some piping systems in which flexible Victaulics are used. Depends on pressure, pipe size, Victaulic type and pipe layout, the annular or total pressure thrust exerting to an equipment may be huge. So if piping stress engineer had access to a similar experience, he/she would consider it. It means others’ experience which was obtained costly previously will make another system safe and cheap; by considering it at the beginning of the project.

Using a proper modeling method of a flexible Victaulic is another example showing the importance of sharing engineering experiences.

Using some computer tools and skills enables engineers to calculate or validate a system when they don’t have any access to professional analysis software. For example Matlab as a powerful mathematical software enables engineers to develop finite element formula for analysis of frames and plates very easily. It may be used for designing of special support or any structure as a handy tool.  Even it includes some toolbox for doing that. They are cheaper and handier than customized analytical expensive software in a place where there is not any.