ISO 657 (Hot-rolled steel sections) is an ISO standard that specifies the tolerances for hot-finished circular, square and rectangular structural hollow sections and gives the dimensions and sectional properties for a range of standard sizes.
This first edition as an International Standard constitutes a technical revision of ISO Recommendation R 657-1:1968. ISO 657 consists of 21 parts integrating any shapes of sections. ISO 657-1 specifies dimensions of hot-rolled equal-leg angles.
Amendments
[edit]- ISO 657-2:1989
- ISO 657-5:1976
- ISO 657-11:1980
- ISO 657-14:2000
- Revisions
- ISO/DIS 12633-2
- ISO 657-14:1982
- Revisions
- ISO 657-15:1980
- ISO 657-16:1980
- ISO 657-18:1980
- ISO 657-19:1980
- ISO 657-21:1983
References
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Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction