Murphy's Laws  - for Engineers


1) If only one bid can be secured on any project, the price will be unreasonable.

2) If a test installation functions perfectly, all subsequent production units will malfunction.

3) In any formula, constants (especially those obtained from engineering handbooks) are to be treated as variables.

4) The most vital dimensions on any plan or drawing stands the greatest chance of being omitted.

5) All delivery promises must be multiplied by a factor of 2.0

6) Parts that positively cannot be assembled in improper order will be.

7) Interchangeable parts won't.

8) Manufacturer's specifications of performance should be multiplied by a factor of 0.5, and salesman's claims for performance by 0.25.

9) Warranty and guarantee clauses are voided by payment of the invoice.

10) The more innocuous the modification appears to be, the further its influence will extend and the more plans will have to be redrawn.

11) If, when completion of a design is imminent, field dimensions are finally supplies as they actually are ­ instead of as they were meant to be ­ it is always simpler to start all over.

12) In designing any type of construction, no overall dimension can be totalled correctly after 4:40 p.m. on Friday.

a) Under the same conditions, if any minor dimensions are given to sixteenths of an inch, they cannot be totalled at all.

b) The correct total will become self-evident at 9:01 a.m. on Monday.

13) The one piece that the plant forgot to ship is the one that supports 75% of the balance of the shipment.

a) Not only did the plant forget to ship it; 50% of the time they haven't even made it.

b) Truck deliveries that normally take one day will take five when you are waiting for the truck.

c) In any structure, pick out the one piece that should not be mismarked and expect the plant to cross you up.

1) In any group of pieces with the same erection mark on it, one should not have that mark on it.

2) It will not be discovered until you try to put it where the mark says it's supposed to go.

3) Never argue with the fabrication plant about an error. The inspection prints are all checked off, even to the holes that aren't there.