DESIGN ALERT ON MECHANICAL DUCT INS ULATION
ISSUE:
Some parts of Section 15250 on mechanical insulation needs updating.
BACKGROUND:
Paragraph 2.2.D of section 15250 on duct insulation is outdated as indicated by Terry
Salli Senior Resident Engineer, Lake City, FL, and confirmed by FM's Standards
Service.
DISCUSSION:
Paragraph 2.2.D refers to mineral fiber insulation for ductwork. It references Federal
specification HH-I-558B which is now superceded by Federal specification HH-I-558C.
In reviewing HH-I-558C it is clear that the Federal specification is now using more ASTM
standards and deleting their own requirements. For instance, paragraph 2.2.D will be
changed now to comply with ASTM C 553 with type II jacketed flexible
blanket, with
k value of 0.31. For humid areas k value will be specified as 0.26.
RECOMMENDATIONS/CONCLUSION:
1. On projects under design, modify paragraph 2.2.D in the project specification for duct
insulation based on ASTM standard C 553. Delete any reference to Federal
specification HH-I-558B.
2. VA master construction specification section 15250 - Insulation, dated 04-95 just
recently updated is being revised further and will carry a new date when it's completed.
FOR ADDIT IONAL INFORMATION:
Contact Satish Sehgal at 202.565.5032 in the Standards Service (187C).
5 May 1995
FM-187C-DA34
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