15817 Add 2.doc

Interior Renovations at U.S. Courthouse

GSA Number: GS-03P-98-CDC-0019

Pittsburgh, Pennsylvania

SECTION 15817

HVAC CASINGS

PART 1 - GENERAL

1.1

SUMMARY

A. This Section includes HVAC casings for field-erected return, outside and relief casings/plenums and for housing mechanical equipment.

B. Related Sections include the following:

1. Division 3 Section for concrete, reinforcement, and formwork requirements.

2. Division 15 Section “Duct Accessories".

1.2

DEFINITIONS

A.

Thermal Conductivity and Apparent Thermal Conductivity (k-Value): As defined in ASTM C 168. In this Section, these values are the result of the formula Btu x in./h x sq. ft. x degF at temperature differences specified. Values are expressed as Btu.

1.

Example: Apparent Thermal Conductivity (k-Value): 0.26.

1.3

SUBMITTALS

A.

Product Data: For factory-fabricated casings, sealant materials, and acoustic liner materials.

B.

Shop Drawings: Include plans, elevations, sections, components, and attachments to other work. Show fabrication and installation details of the following:

1. Reinforcement and spacing.

2. Seam and joint construction.

3. Access doors, including frames, hinges, and latches.

4. Hangers and supports, including methods for building attachment, and casing attachment.

5. Interior lighting, including switches.

C.

Product Certificates: For factory-fabricated casings, signed by product manufacturer.

1. Show sound-absorption coefficients in each octave band lower than those scheduled when tested according to ASTM C 423.

2. Show airborne sound transmission losses lower than those scheduled when tested according to ASTM E 90.

D.

Welding certificates

1.4

QUALITY ASSURANCE

A. Welding: Qualify procedures and personnel according to AWS DI .1, "Structural Welding Code--Steel", for hangers and supports and AWS D9.1, "Sheet Metal Welding Code", for HVAC casing joint and seam welding.

1.5

COORDINATION

A. Coordinate size and location of concrete bases. Cast anchor-bolt inserts into bases. Concrete, reinforcement, and formwork requirements are specified in Division 3.

B. Coordinate installation of roof curbs, equipment supports, and roof penetrations. These items are specified in Division 7.

PART 2 - PRODUCTS

2.1

MANUFACTURERS

A.

In other Part 2 articles where titles below introduce lists, the following requirements apply to product selection:

1.

Available Manufacturers: Subject to compliance with requirements, manufacturers offering products that may be incorporated into the Work include, but are not limited to, manufacturers specified.

2.2

SHEET METAL MATERIALS

A. Galvanized Sheet Steel: Lock-forming quality; complying with ASTM A 653/A 653M and having 090 coating designation; ducts shall have mill-phosphatized finish for surfaces exposed to view.

B. Reinforcement Shapes and Plates: Galvanized-steel reinforcement where installed on galvanized sheet steel casings.

2.3

FACTORY-FABRICATED CASINGS

A.

Description: Double-wall, insulated, pressurized equipment casing.

1.

Available Manufacturers:

a. Bally.

b. McGill AirFlow Corporation.

B.

Panel Fabrication: Solid, galvanized sheet steel exterior shell and solid galvanized sheet steel interior shell; with 2-inch space between shells.

1. Fabricate with a minimum number of joints.

2. Weld exterior and interior shells to perimeter; to interior, longitudinal, galvanized-steel channels; and to box-end internal closures. Paint welds.

3. Exterior Shell Thickness: 0.040-inch minimum.

4. Interior Shell Thickness: 0.034-inch minimum.

5. Fabricate perimeter and interior, longitudinal channel members with galvanized-steel shapes.

6. Fill each panel assembly with insulating material that is noncombustible, inert, mildew resistant, and vermin proof, and that complies with NFPA 90A for flame and smoke.

7. Fabricate panels with tongue-and-groove, continuous self-locking joints effective inside and outside each panel.

C.

Trim Items: Fabricate from a minimum of 0.052-inch galvanized sheet steel, furnished in standard lengths for field cutting.

D.

Access Doors: Fabricate personnel access doors at least 24 by 60-inches and other access doors in sizes indicated.

1. Fabricate doors of same thickness as panels, with a minimum 0.040-inch solid, interior and exterior, galvanized sheet steel shell.

2. Install a minimum of two ball-bearing hinges and two wedge-lever-type latches, operable from inside and outside. Install doors to open against air pressure differential. Install neoprene gaskets around entire perimeters of door frames.

3. Fabricate windows in doors consisting of double-dlazed, wire-reinforced safety glass with an air space between panes and sealed with interior and exterior rubber seals.

E.

Structural Performance: Fabricate plenum to be self-supporting and capable of withstanding internal static pressures as scheduled, without any panel joint exceeding deflection of L/200 where "L" is the unsupported span length within completed casings.

1. Acoustic Performance: Certified by an independent acoustical testing agency listing sound-absorption and transmission-loss characteristics of panel assemblies.

2. Thermal Conductivity (k-Value): 0.26 at 75 degF mean temperature.

F.

Static-Pressure Classifications: Unless otherwise indicated, fabricate HVAC casings according to the following:

1. Before Fans: 2-inch WG.

2. After Fans: 2-inch WG.

PART 3 – EXECUTION

3.1 EXAMINATION

A. Examine concrete bases and roof curbs for compliance with requirements for conditions affecting installation and performance of HVAC casings.

B. Proceed with installation only after unsatisfactory conditions have been corrected.

3.2

INSTALLATION

A.

Install casings according to SMACNA's "HVAC Duct Construction Standards--Metal and Flexible". Comply with recommended spacing of sheet metal screws and with requirements for casing sealing and trim positioning.

B. Apply sealant to joints, connections, and mountings.

C. Field-cut openings for pipe and conduit penetrations; insulate and seal according to SMACNA's "HVAC Duct Construction Standards--Metal and Flexible".

D. Support casings on floor or foundation system. Secure and seal to base.

E. Support components rigidly with ties, braces, brackets, and anchors of types that will maintain housing shape and prevent buckling.

F. Align casings accurately at connections, with 1/8-inch misalignment tolerance and with smooth interior surfaces.

G. Maintain duct seal class integrity throughout casings.

3.3

FIELD QUALITY CONTROL

A.

Perform the following field tests and inspections according to SMACNA's "HVAC Air Duct Leakage Test Manual" and prepare test reports:

1. Conduct tests at static pressures equal to maximum design pressure of system or section being tested. If pressure classes are not indicated, test entire system at maximum system design pressure. Do not pressurize systems above maximum design operating pressure. Give 7-days' advance notice for testing.

2. Determine leakage from entire system or section of system by relating leakage to surface area of test section. Comply with requirements for leakage classification of ducts connected to casings.

3. Remake leaking joints and retest until leakage is equal to or less than maximum allowable.

END OF SECTION 15817

October 26, 2010

Addendum 2 15817- 1 HVAC CASINGS