###### Editorial Note on Part 173

#### Editorial Note:

Nomenclature changes to part 173 appear at 61 FR 14482, Apr. 2, 1996; 66 FR 56035, Nov. 6, 2001; 66 FR 66742, Dec. 27, 2001; and 81 FR 49896, July 29, 2016.

#### § 173.310 Boiler water additives.

Boiler water additives may be safely used in the preparation of steam that will contact food, under the following conditions:

(a) The amount of additive is not in excess of that required for its functional purpose, and the amount of steam in contact with food does not exceed that required to produce the intended effect in or on the food.

(b) The compounds are prepared from substances identified in paragraphs (c) and (d) of this section, and are subject to the limitations, if any, prescribed:

(c) List of substances:

| Substances | Limitations |
| --- | --- |
| Acrylamide-sodium acrylate resin | Contains not more than 0.05 percent by weight of acrylamide monomer. |
| Acrylic acid/2-acrylamido-2-methyl propane sulfonic acid copolymer having a minimum weight average molecular weight of 9,900 and a minimum number average molecular weight of 5,700 as determined by a method entitled “Determination of Weight Average and Number Average Molecular Weight of 60/40 AA/AMPS” | Total not to exceed 20 parts per million (active) in boiler feedwater. |
| Ammonium alginate | |
| Cobalt sulfate (as catalyst) | |
| 1-hydroxyethylidene-1,1-diphosphonic acid (CAS Reg. No. 2809-21-4) and its sodium and potassium salts | |
| Lignosulfonic acid | |
| Monobutyl ethers of polyethylene-polypropylene glycol produced by random condensation of a 1:1 mixture by weight of ethylene oxide and propylene oxide with butanol | Minimum mol. wt. 1,500. |
| Poly(acrylic acid-*co*-hypophosphite), sodium salt (CAS Reg. No. 71050-62-9), produced from a 4:1 to a 16:1 mixture by weight of acrylic acid and sodium hypophosphite | Total not to exceed 1.5 parts per million in boiler feed water. Copolymer contains not more than 0.5 percent by weight of acrylic acid monomer (dry weight basis). |
| Polyethylene glycol | As defined in § 172.820 of this chapter. |
| Polymaleic acid [CAS Reg. No. 26099-09-2], and/or its sodium salt. [CAS Reg. No. 30915-61-8 or CAS Reg. No. 70247-90-4] | Total not to exceed 1 part per million in boiler feed water (calculated as the acid). |
| Polyoxypropylene glycol | Minimum mol. wt. 1,000. |
| Potassium carbonate | |
| Potassium tripolyphosphate | |
| Sodium acetate | |
| Sodium alginate | |
| Sodium aluminate | |
| Sodium carbonate | |
| Sodium carboxymethylcellulose | Contains not less than 95 percent sodium carboxymethylcellulose on a dry-weight basis, with maximum substitution of 0.9 carboxymethylcellulose groups per anhydroglucose unit, and with a minimum viscosity of 15 centipoises for 2 percent by weight aqueous solution at 25 °C; by the “Viscosity of Cellulose Gum” method prescribed in the Food Chemicals Codex, pp. 1128-1129. |
| Sodium glucoheptonate | Less than 1 part per million cyanide in the sodium glucoheptonate. |
| Sodium hexametaphosphate | |
| Sodium humate | |
| Sodium hydroxide | |
| Sodium lignosulfonate | |
| Sodium metabisulfite | |
| Sodium metasilicate | |
| Sodium nitrate | |
| Sodium phosphate (mono-, di-, tri-) | |
| Sodium polyacrylate | |
| Sodium polymethacrylate | |
| Sodium silicate | |
| Sodium sulfate | |
| Sodium sulfite (neutral or alkaline) | |
| Sodium tripolyphosphate | |
| Sorbitol anhydride esters: A mixture consisting of sorbitan monostearate as defined in § 172.842 of this chapter; polysorbate 60 ((polyoxyethylene (20) sorbitan monostearate)) as defined in § 172.836 of this chapter; and polysorbate 20 ((polyoxyethylene (20) sorbitan monolaurate)), meeting the specifications of the Food Chemicals Codex, pp. 825-827. | The mixture is used as an anticorrosive agent in steam boiler distribution systems, with each component not to exceed 15 milligrams per kilogram in the steam. |
| Tannin (including quebracho extract) | |
| Tetrasodium EDTA | |
| Tetrasodium pyrophosphate | |

(d) Substances used alone or in combination with substances in paragraph (c) of this section:

| Substances | Limitations |
| --- | --- |
| Cyclohexylamine | Not to exceed 10 parts per million in steam, and excluding use of such steam in contact with milk and milk products. |
| Diethylaminoethanol | Not to exceed 15 parts per million in steam, and excluding use of such steam in contact with milk and milk products. |
| Hydrazine | Zero in steam. |
| Morpholine | Not to exceed 10 parts per million in steam, and excluding use of such steam in contact with milk and milk products. |
| Octadecylamine | Not to exceed 3 parts per million in steam, and excluding use of such steam in contact with milk and milk products. |
| Trisodium nitrilotriacetate | Not to exceed 5 parts per million in boiler feedwater; not to be used where steam will be in contact with milk and milk products. |

(e) To assure safe use of the additive, in addition to the other information required by the Act, the label or labeling shall bear:

(1) The common or chemical name or names of the additive or additives.

(2) Adequate directions for use to assure compliance with all the provisions of this section.

(f) The standards required in this section are incorporated by reference into this section with the approval of the Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be examined at the Dockets Management Staff (HFA-305), Food and Drug Administration, 5630 Fishers Lane, Rm. 1061, Rockville, MD 20852, 240-402-7500, between 9 a.m. and 4 p.m., Monday through Friday, or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030 or go to: *http://www.archives.gov/federal-register/cfr/ibr-locations.html.*

(1) Dockets Management Staff (HFA-305), Food and Drug Administration, 5630 Fishers Lane, Rm. 1061, Rockville, MD 20852, 240-402-7500, between 9 a.m. and 4 p.m., Monday through Friday:

(i) “Determination of Weight Average and Number Average Molecular Weight of 60/40 AA/AMPS” (October 23, 1987).

(ii) [Reserved]

(2) United States Pharmacopeial Convention, 12601 Twinbrook Pkwy., Rockville, MD 20852 (Internet address *http://www.usp.org*):

(i) Food Chemicals Codex, 7th ed. (2010), pp. 1128-1129.

(ii) Food Chemicals Codex, 7th ed. (2010), pp. 825-827.

[42 FR 14526, Mar. 15, 1977, as amended at 45 FR 73922, Nov. 7, 1980; 45 FR 85726, Dec. 30, 1980; 48 FR 7439, Feb. 22, 1983; 49 FR 5748, Feb. 15, 1984; 49 FR 10106, Mar. 19, 1984; 50 FR 49536, Dec. 3, 1985; 53 FR 15199, Apr. 28, 1988; 54 FR 31012, July 26, 1989; 55 FR 12172, Apr. 2, 1990; 61 FR 14245, Apr. 1, 1996; 64 FR 1759, Jan. 12, 1999; 64 FR 29227, June 1, 1999; 78 FR 71466, Nov. 29, 2013; 88 FR 17723, Mar. 24, 2023]