It is difficult to comprehend but gone are the days when Engineers perform their design calculations prior to asking vendor quotations. Several decades ago, when computers are only for the wealthy, Engineers only have their slide rule or later scientific calculator as a tool in performing their design calculations. Despite some inaccuracies due to the limitations of decimal point, the designs performed during those days exist out-perform their predecessors. This means that the engineers during those time have their basic engineering knowledge laid on stone. Unlike today's engineers that would prefer to have the Vendors perform their design for them. The reason? Vendors are the experts!
Vendor are the experts? Pardon me but I do not trust that statement. Sometimes maybe but not all the time. Moreso, how does the engineer verify the work of the vendor if the engineer does not know the ins and outs of what is being asked from the vendor. The vendor could under size the equipment to gain advantage on price or quote an over-design unit to have a good commercial advantage. How can these be verified?
I remember a long time ago when my manager has been boasting on one of his vendors of electrical heaters giving him always a heater that does the job. I asked him, how do you know? He just answered, it worked! Then I asked again, is it the right size you need? Or you are consuming more electricity than what you are supposed to? As I was already part of the team when a new heater is required, I took the process data from the process department, then performed heater sizing calculations. When the vendor arrive to submit the proposal, I reviewed it and asked questions relevant to the heater design. It looked like that the heater size has a safety factor much much higher than what is required increasing significantly the size of the heater. Ultimately, over size equipment will lead to higher initial cost and operating cost.
As engineers, do you trust your vendors?