The following is an example of the importance of quality assurance. You decide to perform a sewage system project. Seven years earlier, a contractor company built you the same system in high quality in the plan time and cost. You are responsible for the decision without any influence from others.
Is it a good decision to go directly to this company or not? Why? (Please consider the answers to these questions before going to the next paragraphs.)
There are now different multinational companies worldwide in different industries; one such industry is construction. So, every company and every one of us are both a customer and manufacturer or service provider sometimes. For instance, the contractor company provides services to the client, and at the same time this contractor company is a client of the manufacturer for the plumbing equipment, HVAC, ceramic tiles, and other materials and equipment required to complete the project. At the same time, the factory that sells the ceramic tiles is also a client to the mechanical spare parts company to maintain their machines working.
So, a defect in any one of the systems will affect all systems. It is obvious that the quality system should apply to all the companies and organizations, assuming that everyone in the company has a good quality system.
Every company should build its own system to ensure that the product and service is based on specifications, requirements, and satisfaction.
When the quality assurance system is strong, it means that even if anyone in the organization moved or retired, the quality system remains the same.
As an answer to the first question, if this company is a family company with a father and a son, and the son becomes lazy and doesn’t care, the project could be in trouble if his company is sharing in any of the project activity. On the other hand, if he has a real quality system, you can deal with him but an audit should also be done (this is discussed later).
On the other hand, for the multinational company the chairman is usually sitting in a country far away from the project, so quality assurance will be in a document that can be reviewed by an external or internal audit. If there are complaints about the company from the owner, the system should record and solve these complaints.
The purpose of quality assurance is as follows: 
specifications and also to reduce manufacturing cost because it will reduce waste or defective products. In particular, projects have a major impact because in these projects the time factor is very important and may be the main driver of the project.
For example, with hotel construction projects, whatever happens to any day of the total time for the project will have a significant return on the owner. The same is true for oil projects. Therefore, when reducing or not rejecting any product, time is not wasted in removing what had been done or repaired or in negotiations between the team of the contractor and the owner and the supervisory, achieving savings of the total time for the project.
A quality product contributes to building a strong and good relationship between the seller and the client by reducing the number of complaints from the client. But a process that generates repeated complaints from the contractor probably has problems maintaining QA, and a flawed QA system can close off many market opportunities at home and abroad.