Anyone know why the thermal expansion coefficient in API-650 is different than B31.3.

Example, At Design Temperature of 200°F, it has 6.67 instead of 6.38 x 10^-6 per in.-°F per B31.3?

Also, API-650 does not gives the Thermal expansion Coefficient at 70°F. I could not interpolate the values between temperature 70°F and 200°F without it.

Thanks.