"gigantic pressure" is a correct phrase and can be used in written English.
Example: The weight of the boulder placed on top of the door created gigantic pressure, making it nearly impossible for anyone to open it without assistance.
Way above the Tasman Sea, a gigantic high-pressure system moved slowly, while to the northwest an intense tropical low butted against a great monsoon trough that stretched over the north of the continent.
Shareholders themselves are under pressure, and the gigantic holes now appearing in corporate pension funds could give them a joint interest with managements in forcing change and boosting genuine earnings over the longer term.
Uncle Dave saw the whole earth, I think, as a gigantic natural laboratory, where heat and pressure caused not only vast geologic movements but innumerable chemical miracles.
There was a gigantic performance from Gerard Piqué; the "now pressure, now don't" employed by Atlético and their targeting of Sergio Busquets.
That sense of floating amid economic bubbles grew today when a gigantic inflated tent, suspended entirely by air pressure, collapsed at the conference site.
As for Bernie Madoff, what sort of man lay behind that sphinxlike smile, and how had he coped for so many years with the psychological pressure of living with such a gigantic falsehood?
The weapons often start off small and then, under the pressure of competition, may evolve to attain gigantic proportions.
As he got out of the fuel cell-powered Chevy Equinox, he explained that the reason it sounded like a gigantic vacuum cleaner was because a compressor was building up pressure in the fuel cell stack.
This winter, the area gained worldwide surfing renown when low-pressure systems coursing offshore created a series of gigantic waves, as big as anything found in Indonesia, Australia or Hawaii.
