Inhibitex 350

Phosphoric and Sulfamic Passivator

INTRODUCTION.

Inhibitex 350 is a corrosion inhibitor for: · Sulphamic acid · Phosphoric acid · Alkyl phosphoric acids and alkyl acid phosphates such as methyl, ethyl, isopropyl and phosphoric acid phosphates.

Physical Properties

Derivative of fatty amines.

Appearance liquid
Specific gravity at 200C 0.983
Viscosity at 200C 120 cPo
Viscosity at 500C 33 cPo
Freezing point 0°c
Solubility in water soluble
Solubility in Phosphoric acid soluble
Solubility in Sulfamic acid soluble

APPLICATIONS.

Inhibitex 350 is especially recommended for the following applications:

Pickling of steels and their alloys by acid solutions.

Inhibitex 350 is a passivator for sulphamic and phosphoric acid and phosphoric ester employed in acid pickling liquors for steels and alloys.

The scouring of ferrous metals is based on the removal, by acidic solutions, of deposits such as rust formed on the surface. In the absence of an inhibitor, the acid attacks the deposits as well as the base metal, with the following disadvantages:

  • Excessive attack of the metal, which goes into solution and develops cracks and craters at the surface.
  • Rapid drop in activity of the pickling bath by the consumption of the acid in the form of a salt.
  • Metal embrittlement by hydrogen diffusion, causing a loss in mechanical properties such as ductility.

Inhibitex 350 added to Sulfamic or phosphoric acid, or to phosphoric ester, helps to limit the action of the acid to the deposits to be removed alone, and thus to preserve the metal surfaces in contact with the pickling liquor.

Inhibitex 350 helps to improve the wetting of the surfaces to be cleaned.

Descaling of water circuits by sulfamic acid:

Sulfamic acid solutions inhibited with Inhibitex 350 easily eliminate deposits and scale of the calcium and magnesium carbonate type, which are essential components of scale deposits.

The use of very hard waters, not softened by water softeners or sequestering agents, gives rise to scale formation.

This occurs in certain conditions depending essentially on the hardness of the water, temperature, dissolved oxygen and Carbon dioxide.

Scale deposits concern all water circuits, especially open and semi-open heating and cooling circuits, and their development could lead to serious disadvantages such as:

  • Lower heat exchange capacities.
  • Sudden line fractures, boiler explosions, corrosion under scale deposits.
  • Substantial reduction of flowrates by progressive lime clogging

DIRECTIONS FOR USE.

Inhibitex 350 can be added either to the concentrated acid or to the acid solution ready for use.

For phosphoric acid, it is used at the rate of 0.025 to 0.05% of the total volume of the 15% acid solution.

For sulfamic acid, it is used at the rate of 0.01 to 0.025% for a 10% acid solution.

PACKAGING.

Inhibitex 350 is delivered in drums of 200 and 24 Kg.

TEST RESULTS.

Tests were conducted on coupons of cold-rolled unannealed mild steel plates. The coupons, measuring 23 x 50 x 1.5 mm, with 25.2 cm2 developed surface area, and weighing 13. 5g, are polished with 600 grade paper, degreased by acetone and weighed. Suspended by a Teflon tape, they are immersed for the time required in a controlled temperature Pyrex flask containing 350 ml of convenient acid in the required concentration.

After attack, the coupons are again rinsed, dried and weighed. Each test is performed three times.

PROTECTION OF MILD STEEL IN 15% PHOSPHORIC ACID.

Temperature °C Test Time
Inhibitex 350
Weight Loss
Protection %
20
4 days
0%
2820 mg
---
20
4 days
0.025%
158 mg
95
80
4 hours
0%
2582 mg
---
80
4 hours
0.025
231 mg
92

PROTECTION OF MILD STEEL IN 10% SULFAMIC ACID.

Temperature °C
Test Time
Inhibitex 350
Weight Loss
Protection %
20
4 days
0%
1620 mg
---
20
4 days
0.005%
30 mg
98
80
4 hours
0%
2558 mg
---
80
4 hours
0.005%
199 mg
91
80
4 hours
0.025%
118 mg
95