Equipment designed to NCh2369 for mining in San Juan, Argentina: what INPRES-CIRSOC 103 requires and who signs

By Germán Reisenauer, Civil Engineer · November 3, 2026 · EDICI Ingeniería, Paraná, Argentina

Many of the electrical rooms, switchgear, transformers and structures bought by the mining projects in the San Juan Andes are designed and built in Chile, to the Chilean industrial seismic standard: NCh2369. Across the border, that engineering meets a different code, INPRES-CIRSOC 103, which has no equivalence table with the Chilean standard. And the engineer who designed it cannot sign in Argentina. What has to be verified, with which numbers, and who signs.

Which code governs in Argentina, and what for

The Argentine seismic code is INPRES-CIRSOC 103. Its Part I, July 2018 edition, was put into force by Resolution 30/2019, and Resolution 11/2026, which renewed the CIRSOC generation of codes, did not change it. Its scope does not exclude industry: it applies to all new construction in the country (art. 1.2). It is completed by Parts II, III and IV, for concrete, masonry and steel, and by the CIRSOC code for each material.

Four articles frame the case of foreign equipment at a mine site (our translation and summary):

• Works that need special studies (art. 1.2). For works of extraordinary importance, the code is a "fundamental guideline". If the owner has a site-specific seismic hazard study, the spectrum can come from it, and the rest of the code still frames the design.
• Who sets the rules for the work (art. 1.3.2). The local building code governs. Where a work is outside its scope, the code applies by analogy or the competent authority defines it. At a mine site, the question goes to the owner: which authority approves, and what the project design criteria say.
• Who answers for the equipment (arts. 1.3.3.1 and 10.1). The professionals of each specialty, such as installations or equipment, are responsible for applying the code in their area. For electrical or mechanical equipment, Chapter 10 places it on whoever designs or supplies it.
• What it protects (art. 1.1). The objective is to prevent collapse and loss of life. The code states that limiting damage or keeping functions after an earthquake is not an objective. If the owner needs the room to keep operating, that must be requested separately: through the occupancy group, the equipment importance factor or the project criteria.

Source: INPRES-CIRSOC 103 Part I, July 2018 edition, arts. 1.1, 1.2, 1.3.2 and 1.3.3.1, and Commentary C 1.2.

NCh2369:2025 in a few lines

The Chilean seismic standard for industrial structures and installations has been renewed. Exempt Decree No. 12 of the Ministry of Housing and Urban Development, dated February 27, 2026 and published in the Diario Oficial on March 9, declared NCh2369:2025 an Official Standard, except clauses 4.6.2, C.4.6.2 and C.11.6. It has been in force since six months after that publication, September 9, 2026, when NCh2369:2003 ceased to be official.

• Scope. According to the Chilean Steel Institute (ICHA), new industrial structures and installations, ducts and piping, process, mechanical, electrical, control and instrumentation equipment, and their anchorage. Among its principles it names continuity of operation, besides the protection of workers.
• Independent review. Clause 4.6.2 calls for the seismic design of structures, equipment and anchors to be reviewed by specialists independent of the designers. It is one of the three clauses the decree excluded from the official declaration.
• Transition. The decree has no rule for projects in progress. According to ICHA, projects submitted before September 9, 2026 keep the previous version.

For whoever verifies in Argentina, this means two things. Since NCh2369:2025 covers equipment and its anchorage, the Chilean package should contain the forces needed for comparison. But the numbers signed in San Juan come from INPRES-CIRSOC 103.

Source: Exempt Decree No. 12 of 2026, Ministry of Housing and Urban Development of Chile, Diario Oficial of March 9, 2026 (CVE 2778372), operative paragraphs 1 to 3. ICHA (March 12, 2026) and Carey (March 13, 2026) notes on scope and excluded clauses. NCh2369:2025 is a paid standard: its text is not quoted.

Where the project sits: zone, site and occupancy group

The zone comes from Annex A, by department. The Andean departments of San Juan:

Source: INPRES-CIRSOC 103 Part I (2018), Annex A and Table 3.1, with Na = 1.

• Near-fault factors. In zones 3 and 4, Table 3.1 multiplies Ca by Na and Cv by Nv, with Na ≥ 1 and Nv ≥ 1.2. The Commentary explains that active faults in the country are not identified or catalogued, so constant values were adopted for the whole zone. A province that studies its faults may set others.
• The site class comes from the soil report (Table 2.2). A dynamically unstable SF site needs special studies.
• The occupancy group scales the seismic action through γr (art. 2.4). Group A, γr = 1.3, lists "large industries" and power plants among its examples. Group Ao, γr = 1.5, lists emergency power plants and storage of flammable or toxic gases or liquids. As we read it, the electrical room of a large mining plant is group A, and one feeding emergency or safety services is group Ao. The project defines it with the owner, preferably in writing.

The room, as a structure

A modular electrical room on its own foundation is a structure, and it is verified as such. With the equivalent static method, on the plateau of the spectrum, the seismic coefficient is C = 2.5 · Ca · γr / R. For a room with a seismic weight of 300 kN, site type 1, group A:

EDICI arithmetic with Table 3.1, art. 2.4, Table 5.1 and art. 5.1.2 of INPRES-CIRSOC 103 Part I (2018).

Going from R = 3 to R = 1.5 doubles the force; going from Iglesia to Calingasta raises it by 28 %. The Table 5.1 values assume the detailing of Part IV, for steel (art. 5.1). A welded container with sheet walls does not always fit one of those systems. The code leaves the elastic route open: the owner or the designer may choose it, with R = 1.5. As we read it, if the container's system is not recognizable in the table, that is the safe route, and any higher R must be justified in the calculation package.

Two more points that often change from one code to the other:

• Damping. The INPRES-CIRSOC 103 spectrum is for 5 %. For lower damping, art. 3.5.1.2 scales it with fa = [7 / (2 + ξ)]^0.5: 1.32 for 2 % and 1.18 for 3 %. If the Chilean package adopted lower damping, bring that figure along.
• Vertical component. INPRES-CIRSOC 103 defines it as Ev = (Ca / 2) · γr · D (art. 3.5.2) and combines it with the horizontal one: E = EH ± EV, in 1.2 D + f1 L + f2 S + 1.0 E and in 0.9 D + 1.0 E (art. 3.7.1).

The equipment inside: Chapter 10

Panels, switchgear, transformers and HVAC units anchored to the room are not designed with the room's R. Chapter 10 gives them their own horizontal force:

Fp  = Cpk · Wp                          [10.1]
Cpk = Ip · Ca · ap · fhk / Rp           [10.2]
0.75 · Ca · Ip ≤ Cpk ≤ 4.00 · Ca · Ip   [10.3]
fhk = 1 + 2 · z / H                     [10.4]

• ap and Rp come from Table 10.2. For electrical power equipment (substations, panels), ap = 1.0 and Rp = 2.5, the same as for control and instrumentation equipment. A sheet-metal HVAC unit takes ap = 2.5 and Rp = 6.0.
• Ip is 1.5 if the component is needed for life safety after the earthquake, contains toxic, explosive or highly hazardous substances, or belongs to a group Ao structure (art. 10.2.1). Otherwise 1.0. Note that group A does not raise equipment forces: only group Ao does.
• No friction. Supports and attachments resist Fp with no credit for friction from gravity loads (art. 10.3).
• Deformations. The component's drift over its attachment is capped at 1.0 % in group Ao, 1.5 % in group A and 2.0 % in group B (Table 10.3).
• Very heavy equipment. Equipment weighing more than 25 % of the seismic weight of its level is modelled together with the structure (art. 10.1).

An example: an 1,800 kg panel on the floor of the room (z = 0, fhk = 1), with four anchor bolts on a 2.2 × 0.8 m pattern and its centre of gravity 1.2 m above the base:

EDICI arithmetic with Chapter 10, Table 3.1 and arts. 3.5.2 and 3.7.1 of INPRES-CIRSOC 103 Part I (2018): overturning resisted by 0.9 · Wp − Ev, rigid base, shear shared by the four bolts.

On the floor of a low room the minimum of [10.3] governs: the formula gives 0.4 · Ca · Ip and the floor is 0.75 · Ca · Ip. Between Iglesia and Calingasta, the same panel goes from no uplift to tension in its bolts. An HVAC unit on the roof of the room (z = H, fhk = 3) takes 46 % of its weight in Calingasta: there the formula governs. The numbers for any piece of equipment can be run in our equipment seismic force calculator (in Spanish).

Anchors and foundation

The bolts that anchor the room to its foundation, and the equipment to the room, are checked with those forces and with the code of each material (art. 10.3). Anchors to concrete follow Chapter 17 of CIRSOC 201-2025, and anchors in seismic-resistant structures also meet the requirements of INPRES-CIRSOC 103 Part II (art. 17.10). For bolts, CIRSOC 301-2018 does accept ASTM standards, such as A36 for threaded rods and anchor bolts.

The container steel and welding

This is where the most concrete gap usually shows up. For shapes, plates and tubes, CIRSOC 301-2018 lists only IRAM-IAS standards (art. A.3.1). ASTM and ISO standards are accepted for bolts, anchors and threaded rods, and welding filler metal refers to AWS. Since 2005 there has been no equivalence route for other steels. A container built in ASTM steel or in a Chilean grade is not on that list. As we read it, the gap is closed with mill certificates, whatever tests are needed and the owner's acceptance, all documented in the gap report.

Who signs in San Juan

The signature of the engineer who designed in Chile is not valid in Argentina. The verification is signed by a civil engineer registered in the province. In San Juan, professional registration for civil engineering is held by the Colegio de Ingenieros Civiles, created by Law 1972-A. To register they ask for the degree, transcript, scope of practice of the degree, national ID and a background check, and a degree from a foreign university must be revalidated.

What gets signed, in general:

• The seismic verification package under INPRES-CIRSOC 103: the room as a structure, the equipment under Chapter 10, the anchors and, if in scope, the foundation.
• The gap report against the original design: what checks, what does not, and what changes.
• The anchorage and foundation drawings, if they are modified or redone.

The Chilean package stays on file as the manufacturer's background document. If the work needs a permit review or approval, the authority of the jurisdiction defines it (art. 1.3.2); at a mine site, the owner knows which one.

Source: Colegio de Ingenieros Civiles de San Juan website (cicsj.ar), home, registration and legal framework pages, accessed November 3, 2026.

What to send for a quote

• The NCh2369 calculation package: spectrum, R, damping, load combinations and equipment forces.
• The room's fabrication drawings, weight and centre of gravity.
• The equipment list with each item's weight, centre of gravity and anchorage detail.
• Material certificates: shapes, plates, bolts and welding consumables.
• The location: department or coordinates.
• The soil report, or at least the site class.
• The owner's design criteria: the occupancy group assigned to the facility, whether continuity of operation is required, and any site-specific seismic hazard study.

Frequently asked questions

Sources: INPRES-CIRSOC 103 Part I, July 2018 edition, arts. 1.1, 1.2, 1.3.2, 1.3.3.1, 2.4, 3.3, 3.5.1.2, 3.5.2, 3.7.1, 5.1, 5.1.2, 10.1 to 10.4, Annex A and Tables 2.2, 3.1, 5.1, 10.2 and 10.3, and Commentary C 1.2 and C 3.5 (Na and Nv), read in the 2018 edition PDF. CIRSOC 301-2018, arts. A.3.1 and J.3, and CIRSOC 201-2025, Chapter 17. Exempt Decree No. 12 of 2026, Ministry of Housing and Urban Development of Chile, Diario Oficial of March 9, 2026. ICHA, note on the official adoption (March 12, 2026), and Carey, note on the approval (March 13, 2026). Colegio de Ingenieros Civiles de San Juan, cicsj.ar. Accessed November 3, 2026. NCh2369:2025 is a paid standard: its scope and status are cited, not its text. Translations of the Argentine code are ours. The numerical examples are EDICI arithmetic.