Hydraulic manifold material selection chart

The chart of manifold’s ASSY components, provided below is not a rule or a standard, this is just what I usually use in my practice. I decided to share it because this info may be interesting for others.

Hydraulic manifold material selection chart

¹⁾ Not applicable for solenoid operated cartridges because solenoid coils generate a magnetic field, that would be interfered by stainless steel.

Aluminum manifold materials

• Material: 6061-T6/T6511 Aluminum Base Alloy
• Material: 7075-T7 Aluminum Base Alloy

When to use:

• Work pressure < 3500 psi.
• Manifold does not contains thin walls between cavities.
• Manifold welding to ASSY is not required

Benefits:

• Proof pressure rating 6000 psi (420 bar)
• Burst pressure rating: 12000 psi (840 bar)

Material standards references:

• ASTM B211: Aluminum and Aluminum Alloy Bar
• ASTM B221: Aluminum and Aluminum-Alloy Extruded Bars.
• ASTM B308: Aluminum Alloy 6061-T6 Standard Structural Shapes

Aluminum surface finishing

	Clear Anodizing of aluminum alloys in accordance with MIL-A-8625F Type II Class I (not dyed). This is an electrolytic process that provides for increased corrosion resistance. The dimensional increase on the original surfaces (per side) shall be between 2 and 20 µm.
	Black Anodizing of aluminum alloys in accordance with MIL-A-8625F Type II Class II (dyed and sealed). This is an electrolytic process that provides for increased corrosion resistance. The dimensional increase on the original surfaces (per side) shall be between 2 and 20 µm.

Ductile Cast Iron manifold material

Material: ASTM A395 and ASTM A536 Grade 65-45-12.

When to use:

• Work pressure > 3000 psi.
• Manifold has thin walls, or
• Manifold has to be welded to ASSY

Material standards references:

• ASTM A395: Ferritic Ductile Iron Pressure-Retaining Castings for Use at Elevated Temperatures
• ASTM A536: Specification for Ductile Iron Castings

Cast Iron surface finishing

	Dewatering Oil offers limited corrosion protection during shipping and storage. Amount of corrosion protection is minimal and varies depending on the environment it is stored in. This is the standard option for custom integrated packages.
	Chemical Blackening – Black oxide coating offers limited corrosion protection during shipping and storage. Amount of corrosion protection is minimal and varies depending on the environment it is stored in. Chemical blackening is standard on three-letter bodies.
	Trivalent Clear Zinc with Top Sealer is rated for 96 hours of protection per salt fog test per ASTM B117 or ISO 9227 5% saline. Trivalent Clear Zinc with Top Sealer is RoHs compliant.
	Clear Zinc Nickel with Top Sealer – SAE AMS 2417, composition contains 10% to 20% Ni, with clear trivalent chromate treatment is rated for 1000 hours of protection per salt fog test per ASTM B117 or ISO 9227 5% saline. Clear Zinc Nickel is RoHs compliant.

Stainless Steel manifold material

Material: 17-4 PH Stainless Steel – DH1150 Condition

When to use:

• High corrosion resistance is required, and
• Work pressure > 3500 psi, or
• Manifold has thin walls

Material standards references:

• ASTM A370: Mechanical Testing of Steel Products
• ASTM A388: Recommended Practice for Ultrasonic Examination of Heavy Steel Forgings
• ASTM E18: Test Methods for Rockwell and Rockwell Superficial Hardness of Metallic Materials
• NACE Standard MR0175: Sulfide Stress Cracking Resistant Metallic Materials for Oilfield Equipment

Stainless Steel passivation

This passivation process is intended for the removal of ‘free iron’ contamination after machining and fabrication, and to improve general corrosion resistance.

The passivation process shall be performed according to the manufacturer’s documented procedures. The process used shall be in accordance with ASTM A967 – Nitric 2. The parts shall be immersed in a bath containing at least 20% by volume of nitric acid at a temperature of 120ºF – 140ºF (49 – 60ºC) for at least 30 minutes.

Passivation standards references:

• ASTM A967: Standard Specification for Chemical Passivation Treatments for Stainless Parts ASTM A380: Standard Practice for Cleaning, Decaling, and Passivation of Stainless Steel Parts, Equipment and Systems.
• ASTM B117: Test Method for Salt Spray (Fog) Testing